BMW X7 vs. Mercedes-Benz GLS: Complete comparison 2026

The BMW X7 represents the very pinnacle of Munich's luxury SUV lineup, offering an impressive combination of vast interior space, premium materials, and state-of-the-art technology. The Mercedes-Benz GLS, previously sold under the GL-Class designation and often rightfully referred to as the "S-Class of SUVs," is a more than worthy rival with its ultimate emphasis on unrivaled ride comfort, majesty, and prestige. Let's take a detailed look at which of these two exceptionally luxurious giants, at approximately four years of age, fares better in our direct comparison and represents a more attractive choice on the current used car market.

When it comes to full-size luxury SUVs, the BMW X7 and Mercedes-Benz GLS models represent the absolute pinnacle of the European market. Both vehicles possess majestic proportions that ensure immense respect on the road and promise uncompromising interior space. When choosing on the used car market – typically for vehicles from around 2020 to 2023 – it is important to compare how seemingly subtle millimeter differences manifest in daily use.

The Mercedes-Benz GLS has a slight edge in this duel in terms of length. With a length of up to 5,209 mm, it is just under 30 to 60 mm longer than its Bavarian competitor, depending on the specific model year. But for passengers, the most important factor is the wheelbase. In the GLS, this measures 3,135 mm, which is exactly 30 mm more than in the BMW X7. In practice, this benefit translates into slightly more generous legroom, especially for passengers in the second and third rows of seats.

The BMW X7, on the other hand, beats its rival in width. With an impressive width of exactly 2,000 mm, it is a significant 44 mm wider. You will feel this inside the car in the form of excellent shoulder room; on the other hand, the wider body might cause some trouble in older parking spaces or narrow underground garage entrances. Both cars exceed a height of 1.8 meters, providing a very dominant view of the road. Overall, it can be said that the Mercedes scores more with its maximum length and longitudinal comfort, while the BMW benefits from its wide stance and interior width.

When choosing a full-size family SUV from the largest on the market, such as the approximately four-year-old BMW X7 (G07 generation) and Mercedes-Benz GLS (X167 generation) models, luggage compartment volume plays a key role. For buyers planning to use these giants for family vacations, transporting sports equipment, or daily logistics with children, interior practicality is absolutely essential. Although both premium SUVs look majestic from the outside, their approach to interior space differs slightly, which can ultimately affect how much luggage you can pack without stress.

In terms of specific figures, the BMW X7 offers a very generous 750 liters in a standard five-seat configuration, while 326 liters remain after unfolding the third row of seats. When all rear rows are folded, you get a van-like 2,120 liters. In contrast, the Mercedes-Benz GLS makes the most of its even slightly larger dimensions, providing an impressive 890 liters in a five-seat configuration. With seven passengers on board, 355 liters are available, and after folding all rear seats, it creates a total of 2,400 liters. In practice, this means the Mercedes provides space for several extra suitcases or bulkier sports equipment. Nevertheless, both vehicles' specifications are more than sufficient for weekend shopping or a long vacation with the whole family.

An interesting feature of these approximately four-year-old generations (manufactured around 2022) is the integration of modern technology and its impact on the interior. Although both brands widely deployed 48V mild-hybrid technology in these models to reduce fuel consumption, the installation of support batteries and electric motors has not negatively affected the overall trunk capacity. Unlike many plug-in hybrid variants of other models, where you have to sacrifice part of the practicality due to large batteries, the luggage compartment volume here remains preserved across the entire range of engines.

From the perspective of pure luggage capacity, the battle between these two German giants is won by the Mercedes-Benz GLS. Its boxier and longer design allows for significantly more cargo in any seat configuration. While the BMW X7 loses slightly on paper, partly due to its more dynamically styled rear, in the real world, it still represents a massive and fully sufficient family car.

The ability to tow heavy loads is one of the key parameters that customers of large luxury SUVs closely monitor. Whether you plan to tow a large motorboat, an oversized caravan, or a heavy horse trailer, the trailer weight and total towing capacity play a crucial role in the selection process. In this category, roughly four-year-old models of the BMW X7 (G07 generation) and Mercedes-Benz GLS (167 generation) represent the absolute pinnacle of what the current used car market offers.

Looking at the specific numbers, you will find that there are practically no differences between these two rivals. Both manufacturers have homologated their flagship SUVs to the maximum possible legislative limit. Both the BMW X7 and Mercedes-Benz GLS boast a standard and maximum braked trailer weight of 3,500 kg. Logically, the unbraked trailer weight for both competitors represents the European legislative maximum of 750 kg. This value remains completely consistent across all relevant engine variants from 2020 to 2022.

The situation regarding electrified versions is interesting. Unlike some smaller SUVs, where plug-in hybrid variants often suffer from significantly reduced towing capacity due to heavy batteries, these flagships rely primarily on advanced mild-hybrid systems (for example, in the GLS 450 or X7 xDrive40d). These systems do not limit the structural strength or cooling of the vehicle, so even in these more modern versions, there is no reduction in maximum towing capacity, and they remain at a full 3.5 tons.

In practice, these values mean absolute user freedom. A towing capacity of 3.5 tons is, of course, more than sufficient for a weekend purchase of heavy building materials, but above all, it offers huge space for several extra suitcases, safely handles even longer holidays with the largest twin-axle caravans, and is not afraid of professional use. Furthermore, the powerful engines of both vehicles and the standard air suspension ensure that you will hardly even know about the trailer behind you while driving.

Final Summary
From the perspective of towing capacity, the battle between the BMW X7 and Mercedes-Benz GLS is absolutely equal and has no clear winner. Both vehicles offer an identical 3,500 kg, which is the figurative ceiling for passenger cars. Your final choice of the ideal "tow car" should therefore depend more on specific brand preferences, overall control ergonomics, or the range of smart assistance systems for easier reversing with a trailer, which both brands handle in slightly different ways.

BMW X7 and Mercedes-Benz GLS offer exceptionally sophisticated engine palettes, where high performance, refinement, and increasingly electrification play a major role. For those interested in used cars approximately four years old (around the 2022 model year), it is essential that both manufacturers have widely implemented mild-hybrid (MHEV) systems into their power units. These technologies help reduce fuel consumption and ensure smoother starts without compromising the overall dynamics of the large SUV. All models from both brands rely exclusively on intelligent all-wheel drive (xDrive for BMW, 4MATIC for Mercedes) and modern multi-speed automatic transmissions. While the BMW X7 benefits from the more dynamic character of its excellent inline-six and V8 engines, the Mercedes-Benz GLS counters with the velvety operation of the EQ Boost system and the immense pulling power of its diesel and petrol units. Whether you are looking for a more economical diesel for long motorway journeys or a powerful V8 for the ultimate experience, both brands can deliver perfectly.

BMW X7 Engines

The foundation of the range for the G07 generation are brilliant turbocharged inline-six engines, topped by flagship V8s. In the used car market, the xDrive30d diesel engines (with 195 kW, later increased to 210 kW) and the more powerful xDrive40d variant, which delivers a sovereign 250 kW and 700 Nm of torque, are particularly popular. Petrol six-cylinders are ideally represented by the xDrive40i model. For sports driving enthusiasts, the M Performance division prepared models designated M50i and the newer M60i, which send a crushing 390 kW (530 hp) to all four wheels. If you are tempted by the absolute diesel peak, you might come across the unique quad-turbo diesel version M50d, boasting an impressive 294 kW and 760 Nm. However, it must be emphasized that according to historical data, production of the M50d engine was definitively ended in late 2020. If you are looking for a car roughly four years old (2021/2022 models), you will no longer encounter the M50d – its role for more demanding drivers has been successfully taken over by the more efficient xDrive40d version. All engines are paired as standard with the lightning-fast eight-speed Steptronic automatic transmission.

Mercedes-Benz GLS Engines

The Mercedes-Benz GLS generation X167 approaches power unit design with the same majesty as the vehicle itself. Among used cars, the reliable inline diesel six-cylinders GLS 350 d and the more powerful GLS 400 d, which produces 243 kW and offers the same 700 Nm of torque as the diesel equivalent from BMW, enjoy great popularity. Those who prefer petrol engines will very often reach for the GLS 450 model, supplemented by a starter-generator with EQ Boost technology, or choose the massive GLS 580 V8 delivering a massive 360 kW (489 hp) and 700 Nm. When examining newer model years, you may notice that from approximately 2023, the range expanded with a new diesel variant, the GLS 450 d. This model achieves an excellent output of 270 kW and 750 Nm of torque, but given its short history on the market, it will be more or less unavailable in the spectrum of four-year-old used cars. For customers without financial compromises, Mercedes has the AMG GLS 63 in reserve, crushing the asphalt with 450 kW (612 hp). The entire range of units uses the excellently tuned nine-speed 9G-TRONIC transmission as standard.

Choosing the right engine is a key decision for long-term satisfaction with nearly 2.5-ton luxury SUVs. Both manufacturers offer a wide range of power units from more economical six-cylinders to top-of-the-line V8s, but for the market of roughly four-year-old used cars, refined inline six-cylinders supported by mild-hybrid technology prove to be the best choice. These engines offer an excellent balance between everyday dynamics, real-world fuel consumption, and mechanical reliability, without the astronomical service costs that often accompany V8s.

For the BMW X7, we recommend: xDrive40d (250 kW)

The 3.0-litre inline six-cylinder diesel (engine code B57) with mild-hybrid technology is an absolutely ideal choice for the massive X7. This version appeared on the market in 2020 and successfully replaced the older xDrive30d and the more complex quad-turbo M50d version, whose production in this generation gradually ended.

• Why it's the best choice: The engine offers an ideal balance. With an output of 250 kW (340 hp), the car has more than enough dynamics even when fully loaded, while maintaining excellent reliability thanks to the robust construction of the B57 engine and great software tuning with the ZF eight-speed transmission.
• Technical advantages: The car impresses with a massive torque of 720 Nm available from as low as 1,750 rpm. In real-world driving, the fuel consumption is pleasing, staying at very reasonable values around 8 to 9 litres per 100 km for such a heavy all-wheel-drive vehicle, which is an exceptional result by the standards of the luxury cruiser class.
• Known risks and weaknesses: As it is a modern diesel, the emission control system with a diesel particulate filter (DPF) and EGR valve is prone to gradual clogging during frequent short city trips. When buying a used car, always insist on a professional diagnosis of the DPF status and the condition of the injectors. A clogged filter is revealed by more frequent regeneration starts and rougher operation. Regularly including longer highway trips significantly extends the life of these components.
• Who it's ideal for: This engine is perfect for families and drivers who frequently travel long distances. The extremely quiet operation of the diesel six-cylinder and the huge range on a single tank make it the perfect companion for swallowing hundreds of highway kilometres in one go.

For the Mercedes-Benz GLS, we recommend: GLS 450 4MATIC (270 kW)

From the perspective of the market for roughly 4-year-old cars (manufactured between 2020 and 2023), we recommend choosing the 3.0-litre inline six-cylinder petrol engine in the 167 model series. It is worth noting that the currently recommended diesel alternative, the GLS 450 d, only entered the range at the end of 2023 and will therefore not be easily found on the regular used car market. However, the petrol engine is exceptionally well-suited to the GLS's opulent character.

• Why it's the best choice: Compared to the extremely expensive and maintenance-intensive V8s, this mild-hybrid six-cylinder (M256) offers almost silent operation, exemplary smoothness, and solid mechanical reliability. This velvety petrol engine fits the character of the car, which places absolute emphasis on a smooth ride and S-Class level comfort, better than anything else.
• Technical advantages: The output of 270 kW (367 hp) and torque of 500 Nm are linearly supported by the EQ Boost system, i.e., an integrated starter-generator. The car accelerates perfectly smoothly, and the start-stop system works without the slightest vibration. Furthermore, the engine does not use traditional belts – components such as the air conditioning compressor or water pump are driven electrically, which increases operating efficiency and reduces the number of mechanical parts subject to normal wear and tear.
• Known risks and weaknesses: When choosing a used car, increased attention should be paid to the 48V electrical system. Its malfunctions manifest as error messages on the dashboard, often directly warning of the 4MATIC drive's malfunction. During a test drive, verify trouble-free warm starting and have the fault memory read at a service centre. Due to direct fuel injection, the engine itself has a slightly "clickier" sound when cold, which is, however, its natural characteristic. It is also necessary to expect a real average consumption of around 11 to 12 litres per 100 km.
• Who it's ideal for: The petrol GLS will be most appreciated by calmer drivers looking for absolute silence and uncompromising insulation from the outside world. It also serves well in mixed family use involving city driving and shorter trips, where the petrol engine, unlike the diesel, does not face complications with a clogged particulate filter.

When choosing giant luxury SUVs like the BMW X7 and Mercedes-Benz GLS, it is necessary to account for the fact that official laboratory fuel consumption figures often differ significantly from real-world results. Physics simply cannot be cheated – we are talking about vehicles with a curb weight of around 2.5 tons and a massive frontal area. To get a more accurate picture of what awaits you at the gas station, we looked at real-world operating data based on the experiences of drivers themselves from the community platform Spritmonitor.de, which we compared and averaged with our internal database figures for vehicle generations available on the nearly new used car market (roughly four years old, or the closest younger variants).

Data source: Spritmonitor.de

Clear dominance of diesel and surprising parity

A very clear trend is evident from the data above, where we have ranked the data from the most economical diesel versions to pure gasoline powertrains. Although diesel engines are currently in decline in many markets, they make absolute sense in the segment of such massive cars.

• Diesel six-cylinders: The BMW X7 xDrive40d and Mercedes-Benz GLS 450 d models can move these massive road yachts with a real-world consumption of under 8 liters per 100 km. Given their dimensions and all-wheel drive, this is a fantastic result.
• Gasoline base models: For standard gasoline variants (xDrive40i and GLS 450), the average consumption already moves towards the 10-liter mark. Smaller turbocharged units would struggle with the high weight here, which is why both manufacturers rightly rely on proper three-liter six-cylinders that can handle the weight well without unnecessarily large fluctuations in consumption.
• Powerful eight-cylinders: If you opt for a more powerful V8, such as the tested generation of the BMW X7 M50i, you must be prepared for a real-world consumption above the 12-liter mark.

An interesting and somewhat surprising finding is how extremely evenly matched both models are. The differences between BMW and Mercedes for direct competitors amount to a maximum of two-tenths of a liter. The energy efficiency of both automakers has thus been brought almost to perfection in these generations.

What does this mean for the average driver?

The decisive factor for choosing the ideal engine should primarily be how the vehicle will be used. If you are a highway traveler who clocks up tens of thousands of kilometers across Europe annually, diesel engines labeled "d" are the clear choice in terms of operating costs and a much higher total range per tank.

For urban and suburban drivers who mostly drive shorter routes and want to avoid potential future problems with diesel particulate filters (DPF), a quieter gasoline alternative may make more sense. However, it is naturally necessary to expect that during frequent stop-and-go traffic in jams, the trip computer will easily show values well above the ten-liter mark. And although customers of such premium vehicles usually don't count every penny, the diesel variants clearly demonstrate that even operating a massive SUV can be unexpectedly cost-effective.

In conclusion, fuel consumption itself will likely not be the main decision criterion that should tip the scales. Both luxury SUVs offer excellently optimized power units with consumption that differs by absolutely negligible margins. Personal design preferences, the behavior of a specific chassis, and the current range of equipment available on the used car market will play a much more important role in the final selection.

Both of these majestic SUVs represent the pinnacle of their respective brands' lineups, which is naturally reflected in their purchase prices. If we focus on the used car market and look for vehicles roughly four years old (production year around 2021 to 2022), we encounter models that have already experienced their most significant depreciation. For a used car buyer, this represents an interesting opportunity to enjoy maximum luxury at a fraction of the original new car price.

BMW X7 (G07 generation, pre-facelift)
The supply of used BMW X7s on the European market is quite extensive. Prices for four-year-old examples currently start at approximately €58,000. For this amount, you typically get the base diesel version, the xDrive30d, with slightly higher mileage. The more popular and powerful xDrive40d (often with the attractive M Sport package and reasonable mileage) will cost you roughly €66,000 to €78,000. If you desire the top-of-the-line M50i V8, be prepared to pay at least €82,000.

Mercedes-Benz GLS (X167 generation, pre-facelift)
Large SUVs with the three-pointed star traditionally hold their value slightly better on the used market, and the GLS is no exception. Prices for roughly four-year-old vehicles start around €66,000 for the most modest diesel variants, the 350 d. The much more sought-after 400 d six-cylinder diesel with richer equipment (very often in the AMG Line) ranges from €74,000 to €91,000. Additionally, a unique feature of Mercedes is the ultra-luxurious Maybach 600 version, which plays in a league of its own on the used market, with prices often exceeding €124,000 even after several years.

Estimated prices for 4-year-old models (mileage approx. 80,000 – 120,000 km)

When choosing between these two premium cruisers, however, you should not just look at the lowest price tag. A crucial factor for the purchase should be a verifiable and complete service history. Potential out-of-warranty repairs of complex technologies, such as the sophisticated air suspension or the rear-axle steering system, can very quickly wipe out the initial savings from the purchase.

In the premium family SUV segment, a top-tier level of passive and active safety is automatically expected. Generally, vehicles in this class commonly achieve the maximum five-star Euro NCAP rating (which, after all, was confirmed by the smaller siblings of both models from which these vehicles are technically derived). However, when evaluating the safety of used cars, it is always essential to perceive the context and the year of testing. The Euro NCAP methodology evolves dynamically and becomes stricter over time. While older tests focused mainly on the passive resistance of the bodywork, modern protocols strictly require reliable active assistants – including, for example, more demanding frontal collisions with a mobile barrier, detailed detection of cyclists, or crisis scenarios directly at intersections. Percentage results across different years are thus never directly comparable.

BMW X7
The largest Bavarian SUV is produced in smaller volumes and at a very high purchase price, which is why the independent organization Euro NCAP has never officially tested it for economic and capacity reasons. In practice, its safety potential is derived from its technical donor – the BMW X5 model, which underwent crash tests in 2018 and took home an excellent five stars. For the approximately four-year-old X7, although exact percentages from the latest testing facilities are missing, the car offers an excellently rigid structure. Its arsenal is complemented by highly advanced systems such as forward collision warning, precise lane keeping, and autonomous emergency braking. However, given its design date, the model has not passed the most modern certifications for evasive maneuvers in urban intersections.

Mercedes-Benz GLS
An identical situation can be observed with the Mercedes GLS. This Stuttgart giant has also not undergone laboratory Euro NCAP crash tests due to its exclusive market position. However, its robust chassis and electronic architecture come from the GLE model, which excelled in tests in 2019 and received a full five stars (moreover, with top-tier 91% adult protection and 90% child protection). The Mercedes-Benz GLS elevates this level with its massive weight, which brings a huge physical advantage to the occupants in the event of a collision with a standard-sized car. Furthermore, the technologies hidden in the Driving Assistance package are among the best on the used car market – the car can reliably prevent collisions, monitor blind spots, and react to sudden obstacles.

Final Comparison
Declaring a safer car purely based on laboratory numbers is not possible, as neither of the flagships can boast official tests. However, both approximately four-year-old used cars possess the most comprehensive safety package available on the market. Mercedes-Benz slightly benefits from a longer history of implementing predictive safety assistants, while BMW pleases with stable and absolutely precise calibration of its radars. Both models easily meet the demands of even the most discerning families.

In addition to standard luxury equipment, each of the models offers more than just basic functions and premium materials, with both manufacturers taking a very distinctive approach to bringing customers maximum added value and a technological edge.

BMW X7: Innovative Details and Dynamic Character

The large SUV from Munich does not try to hide its sporty roots, but at the same time, it brings a range of highly practical and visually stunning solutions to family life.

• Practical design and smart solutions: The BMW X7 features the brand's signature electrically operated two-piece tailgate (Split Tailgate). The lower section makes loading heavy items easier and serves as a practical bench on trips with a load capacity exceeding 250 kg.
• Assistance systems and telematics: A significant aid when maneuvering this giant vehicle daily is the Reversing Assistant. The system can remember the last 50 meters driven forward (up to a speed of 36 km/h) and then reverse completely autonomously along the exact same trajectory.
• Unique comfort: For the maximum comfort of all passengers, the BMW X7 offers a five-zone automatic climate control system, unique on the market, which gives passengers in the third row of seats a completely independent control panel. At night, the Sky Lounge panoramic glass roof stands out, with more than 15,000 integrated LEDs creating a starry sky effect, the color of which changes according to the selected ambient lighting.
• Chassis and sports packages: While the standard air suspension smooths out bumps, the optional Executive Drive Pro system with active roll stabilization gives the car unexpected agility. For driving enthusiasts, top-of-the-line M division engines (such as the M50i) are available, which defy the laws of physics associated with a weight exceeding 2.5 tons through their driving performance.

Mercedes-Benz GLS: A Technological Oasis and Ultimate Luxury

The competitor from Stuttgart focuses on creating the perfect sanctuary from the outside world. Its technological innovations primarily aim for unrivaled passenger care and predictive vehicle behavior.

• Smart features for every day: Mercedes-Benz has equipped the GLS model with an ingenious Car Wash mode. With a single press of a button on the center display, the suspension rises to its highest position (for easier wheel arch cleaning), mirrors fold in, windows and the sunroof close, the rain sensor is deactivated, and the climate control switches to air recirculation.
• Advanced infotainment and interface: The MBUX multimedia system with artificial intelligence offers augmented reality (AR) for navigation, where navigation instructions and arrows are projected over a camera image of the real street directly onto the display. The system is complemented by a voice assistant that responds to the command "Hey Mercedes," which understands natural speech.
• First-class wellness: The Energizing Comfort feature connects seat massage programs, ambient lighting, the audio system, and an integrated air fragrancer into comprehensive relaxing or invigorating programs designed to reduce driver fatigue on long journeys.
• Revolutionary chassis: A breakthrough feature is the optional E-Active Body Control active hydropneumatic suspension. Using cameras, it scans the road ahead and can adjust the damping for each wheel individually before the car hits a bump. Linked to the system is the famous "bouncing" assistant (Free-driving assist) – if the car gets stuck in deep sand or snow, the suspension begins to rhythmically raise and lower the vehicle, helping to gain traction for recovery.

BMW X7 is an ideal choice for those who demand a certain level of driver engagement and dynamics even from a huge luxury SUV. It scores mainly with fantastic engines, top-notch infotainment, and a premium feel, making it a perfect highway cruiser with a slightly sporty touch.

Mercedes-Benz GLS represents the absolute pinnacle in family comfort, maximum spaciousness, and a peaceful ride. It will primarily appeal to buyers whose main priority is luxurious and undisturbed travel, and who realistically plan to frequently use the full capacity of the vehicle for a large family.

Based on our long-term experience from service networks, recall reports, and outputs from our service for independent technical inspection of the car, we have compiled an overview of the most common problems you should watch out for with these luxury SUVs at around four years of age.

The BMW X7 (G07 generation), despite its massive build, is a technically very advanced car, which brings specific risks associated primarily with complex electronics and extreme stress on chassis components.

• Air suspension: The standard air suspension is prone to air leaks from the bellows or excessive compressor wear as mileage approaches 100,000 kilometres. This manifests as longer inflation times at startup or the vehicle sagging on one side during prolonged parking.
• Engines and cooling: The petrol straight-six engines (B58) are considered very reliable, but they occasionally struggle with minor coolant leaks around the water pump. For diesel engines (B57), carefully verify the history of recall actions – the exhaust gas recirculation (EGR) cooler can leak coolant. Petrol V8s are sensitive to oil quality and change intervals.
• Rapid wear of consumables: The BMW X7 weighs over 2.5 tonnes. Therefore, expect very rapid wear of brake pads and the discs themselves, potentially as early as 40,000 kilometres. The tread on large tyre sizes disappears just as quickly.
• Electronics and interior: In early model years (2019–2020), owners complained about the iDrive system freezing and smartphone connectivity issues. Most were resolved by over-the-air (OTA) updates. Among mechanical elements, the soft-close door mechanism or the panoramic sunroof blinds occasionally malfunction.

The Mercedes-Benz GLS (X167 generation) shares its architecture with the smaller GLE model, and its biggest pain points in four-year-old used cars are concentrated in the advanced onboard systems and the complex 48V onboard network.

• Electrification and 48V network: Petrol engines use the EQ Boost mild-hybrid system. Failures of the integrated starter-generator (ISG) or the 48V battery itself are very common and, unfortunately, expensive. If the system fails, the vehicle can become completely immobile.
• E-Active Body Control system: The standard Airmatic air suspension suffers from similar ailments as the BMW (air leaks). However, the optional E-Active Body Control active suspension represents a major risk. While the system is fantastic for driving, it relies on powerful hydraulics powered by the aforementioned 48V network. Any repair of pumps or dampers is astronomically expensive.
• MBUX Infotainment: Complaints about onboard displays freezing, system restarts while driving, or malfunctioning voice control are more frequent in the GLS than in its Bavarian competitor. For many vehicles, this was resolved by new software, but for some, the entire infotainment hardware unit had to be replaced.
• Interior quality: Although it is a flagship model, reports of creaking plastics around the dashboard, local failure of LED segments in the ambient lighting, and unusual noises from the electric folding mechanism of the third row of seats appear in used cars with higher mileage.
• Clogging in diesel engines: The six-cylinder diesels (OM656) are very robust but absolutely hate short city trips. They quickly experience clogging of the diesel particulate filter (DPF) and failures of sensitive NOx sensors.

When buying a used car, a thorough inspection is key. Here are some specific points to focus on for these two luxury models, where a comprehensive car audit is almost a necessity given their technological complexity.

When choosing a BMW X7:

• Condition of the air suspension: Due to its extreme weight (over 2.4 tons), the air suspension is under heavy stress. During the test drive, try all height modes. If the car rises slowly or the compressor runs unnaturally loudly, it may signal an air leak or a worn compressor.
• Cooling system and leaks in V8 engines: Especially with older M50i versions (G07 generation), pay close attention to coolant leaks or excessive oil consumption. After the engine has warmed up, check for traces of operating fluids under the car or on the engine block.
• Wear of consumables: A large and heavy SUV means fast wear of brakes and tires. A physical inspection of a used car should include measuring the thickness of the brake discs and checking for unevenly worn tires, which can also indicate misaligned wheel geometry.
• iDrive system functionality: The 7th generation iDrive infotainment is generally reliable, but older software versions from the first years of production could occasionally freeze or spontaneously restart the displays. Test whether the system responds smoothly to touch and the rotary controller, and ask about the date of the last update.
• Integral Active Steering: If the car is equipped with rear-axle steering, try driving at a walking pace and turning the steering wheel to full lock. Listen for any unusual noises, squeaks, or pops coming from the rear of the car. The system must operate quietly and without jerky movements.

When choosing a Mercedes-Benz GLS:

• Reliability of the 48V network (EQ Boost): Most engines of the X167 generation rely on a mild-hybrid system with a 48V battery. If the system fails, the car often won't start at all. Repeatedly test the start-stop system and the smoothness of acceleration from a standstill. For models from the first years of production, it is worth checking whether the car has reported problems with this network under warranty in the past.
• Complex Airmatic and E-Active Body Control suspension: These systems are the pinnacle of comfort, but repairs can reach astronomical amounts. An independent technical inspection of the car must reveal any cracks in the bellows or leaks from the adaptive dampers. Changing the ride height must occur smoothly.
• 9G-Tronic automatic transmission behavior: During the test drive, focus on the smoothness of shifting, especially when braking into an intersection and downshifting from 3rd to 2nd and from 2nd to 1st gear. Jerking, kicking, or long delays in a GLS can often be resolved with a software update, but they can also mask more expensive wear of the mechatronics.
• MBUX infotainment stability: The MBUX interface contains a huge number of functions. For cars around four years old, thoroughly click through the menus, start the camera system, navigation, and connect your phone. Some units suffered from connection drops or freezing of the entire center display.
• Interior craftsmanship and unwanted noises: Although the GLS belongs at the absolute top of the brand's range, many owners have pointed out squeaking plastics on the center console, dashboard, or rear electrically operated seats when driving over bumps. Drive the car over a section of poor asphalt without the radio on.

Sources: ADAC, auto.cz, denik.cz, autorevue.cz, automix.cz, autickari.cz

This article was prepared using artificial intelligence tools. The section guarantor is Petr Dušek.