Mercedes-Benz GLS-Class vs BMW X3

What's the difference?

The GLS450d impresses as an entry-level grade, as it’s a more family-friendly allrounder than the specialised AMG and Maybach variants. Its combination of a torque-rich diesel 48V hybrid drivetrain, air-cushioned suspension and plush interior are as well suited to luxury urban travel as they are to grand touring, where its heavy towing and generous load-carrying capabilities can shine. Whether it’s worth around $200K drive-away, only those who shop at the top end of town can decide.

This is a highly competent all-rounder, given that it has the comfort and practicality for urban family duties yet with its revered M breeding can produce a level of performance which, in competent hands, could hold its own at a track day where its capabilities could be safely explored.

This is an imposing vehicle in extravagant S-Class tradition, riding on an expansive 3135mm wheelbase and stretching more than 5.2 metres (5215mm) long and more than 2.0 metres (2030mm) wide with a turning circle that's nudging 13 metres.

However, it’s just under 1.8 metres (1798mm) tall, so there’s no clearance issues when accessing multi-storey carparks. And with its side-steps (or ‘running boards’ in nostalgic Benz speak) most adults can step rather than climb aboard, although passengers of shorter stature during our test noted that assist handles on the A and B pillars would be handy.

Central to its sophisticated chassis design is adaptive air suspension, which uses a pneumatic or ‘airbag’ form of springing with adaptive damping to continuously optimise ride comfort and handling response according to road conditions and driving dynamics (see Driving).

The GLS’s styling is clean and uncluttered with tasteful restraint evident in its chrome and satin-chrome highlights, yet it projects a majestic quality with its prominent four-louvre grille and elegantly spoked alloy wheels.

The spacious and sumptuous seven-seat interior is visually pleasing and practical, with a subtle blend of surface treatments, contrasting tones, lots of soft-touch surfaces and exposed stitching. This is combined (thankfully) with physical dials, switches and ‘piano key’ buttons to control numerous interior functions, in preference to distracting touchscreen prompts.

The fourth-gen X3, which has a lighter but stiffer body, shares the same wheelbase as its third-gen predecessor but at 4755mm end-to-end it's 34mm longer and it's 29mm wider.

It’s also 25mm lower, which combined with front and rear track-width increases and adaptive suspension damping to sharpen the handling underlines its sportiness and driver appeal, despite a substantial 2055kg kerb weight.

The new exterior design is characterised by short overhangs, flush door handles, a larger ‘split kidney’ grille, new LED taillights and L-shaped light elements for the LED headlights.

The new interior design is a classy mix of soft-touch materials and high-gloss hard surfaces in tastefully contrasting tones. The seats are upholstered in a new synthetic leather called 'Veganza' ('Espresso Brown' in our example) which according to BMW requires 85 per cent fewer CO2 emissions to produce than genuine leather (which is still available as an extra-cost option).

Combined with subtle use of ‘Magnolia’ fine-wood trim inserts, satin chrome, piano black, blue/red M highlights and slender ambient light-strips, it’s a cabin that exudes opulence.

Although it has a hefty 2655kg kerb weight, our test vehicle’s 3420kg GVM rating provides a useful 765kg of load capacity, which should comfortably absorb the combined weight of up to seven occupants and light luggage. Or with the third row of seating folded, five occupants and heavier luggage.

It’s also rated to tow up to 3500kg of braked trailer and with its sizeable 6920kg GCM (or how much weight it can legally carry and tow at the same time) it can carry its maximum load while towing its maximum trailer weight.

So, that’s commendable practicality, given it would be well suited to owners that need to tow large caravans, boat trailers, horse floats etc in style without having to compromise much (if at all) on either passenger numbers or luggage capacity.

Driver and front passenger space and comfort is exceptional, as you’d expect. Storage includes a large glovebox plus a bottle holder and bin in each door. The front of the centre console has two USB-C ports, wireless phone charging and heated cupholders, while the rear of the console has a large storage box with a third USB-C port and padded lid that doubles as a comfy elbow rest.

Even tall passengers in the second row of seating enjoy spacious comfort, given I’m 186cm and with the driver’s seat set in my position I have ample knee clearance, foot room and head space.

However, the central passenger must contend with a transmission tunnel in the floor and shoulder room would be squeezy for three large adults, which is okay for short trips but a maximum of two would be ideal for longer journeys.

The rear of the centre console also treats second-row passengers to a pair of USB-C ports, adjustable air-vents and a control panel that allows independent climate adjustment.

There’s also a large bin/bottle holder in each door plus storage nets on each front seat backrest. The centre seat backrest folds flat to allow long items (skis etc) to slot between the outer backrests. And it also serves as a fold-down armrest, containing two cupholders and a lidded slimline compartment that’s ideal for hidden phone storage.

The third row is uncommonly spacious, even for tall people, with padded armrests on each side containing cup holders and twin USB-C ports.

The carpeted rear luggage area has four load-anchorage points, a first aid kit and 12v socket. With the third-row seats upright it offers 355 litres of load volume, which increases to 1350 litres with the third row folded and 2400 litres (or 2.4 cubic metres) with both the second and third rows folded.

This would make a great family weekend escape machine, for which BMW quotes a 645kg payload rating. It’s also rated to tow up to 2500kg of braked trailer, which could pose a challenge given the relatively low 100kg tow-ball download limit (TBD is typically around 10 per cent of trailer weight).

BMW also does not publish a GCM figure (how much it can legally carry and tow at the same time) so we can’t confirm if it can carry its maximum payload while towing its maximum trailer weight.

Even so, the M50 has a useful-sized luggage area which offers up to 570 litres (or 0.57 cubic metres) of load volume with the rear seat upright.

This expands to 1700 litres (or 1.7 cubic metres) with the rear seat folded flat, which can be handy for a multitude of tasks like transporting a mountain bike or hauling home flat-pack furniture.

There’s comfortable space for the driver and front passenger, along with useful storage including large bottle-holders and bins in each front door.

The centre console has two small-bottle/cupholders plus wireless phone-charging and a pair of USB ports. There's also a glove box plus another box at the rear of the console with a padded lid that doubles as an elbow rest.

The rear bench seat is surprisingly spacious, given that I’m 186cm tall and when seated behind the driver’s seat in my position I still have about 40mm of knee clearance, which is optimised by the concave shape of the front seat backrests.

The spacious and airy feel is enhanced by the ‘panorama’ glass roof which spans the full length of the seating area and allows generous headroom even for tall people.  

However, shoulder room is tight for three adults and the centre passenger’s feet must contend with the transmission tunnel, so even though it would be fine for three kids we’d suggest a limit of two adults for longer trips.

Rear passengers get privacy glass and pull-up roller sunshades, large-bottle holders and bins in each door plus net-type pockets and anchorage points for media devices on each front seat backrest. There are also two small-bottle/cupholders in the fold-down centre armrest.

The rear of the centre console has two USB ports, adjustable air-vents plus controls for zone temperature, airflow preferences and seat-heating.

The bench seat features a 40/20/40 split, which allows the centre backrest to fold forward independent of the two outer backrests to allow long loads like snow skis, home hardware etc to be carried if securely fastened.

A power tailgate provides access to the luggage area, which is equipped with a handy 12-volt accessory socket plus load-anchorage points front and rear, extra storage nooks for small items on either side and a retractable roller-type load cover. Overall, this vehicle offers good practicality for family duties.

Our X3 M50 xDrive test vehicle, finished in new 'Dune Grey Metallic', comes standard with a 3.0-litre turbocharged inline six-cylinder petrol engine incorporating 48-volt mild-hybrid technology, plus an eight-speed automatic and permanent all-wheel drive for a list price of $128,900.

You’d expect a high performance prestige vehicle costing six figures would be packed with desirable standard features and the M50 xDrive delivers, starting with big 21-inch 'M' lightweight alloy wheels shod with wide 285/35R21 tyres.

However, there’s no room for a spare (not even a space-saver) so you get a tyre repair kit instead.

The standard equipment list also includes adaptive LED headlights (with matrix high-beam and blue design detailing), a power tailgate, an ‘Iconic Glow’ illuminated kidney grille with M-specific elements, quad exhaust outlets, a panorama full-length (fixed) glass roof, a choice of six premium metallic paint colours and more. The 'M Sport Pro' visual enhancement package is also included.

Step inside and the driver is treated to a head-up display and an elegantly curved digital dash display, which spans about two-thirds of the cabin's width. It seamlessly incorporates a 12.3-inch driver’s instrument display (made from recycled polyester) and 14.9-inch multimedia display controlled by BMW’s latest 'iDrive System 9' software.

Premium audio is provided by a 15-speaker 750-watt Harman Kardon surround sound system, which includes digital radio and wireless Apple/Android connectivity. There’s also wireless phone charging.

The driver gets a thick leather-rimmed and heated 'M Sport' flat-bottom steering wheel and the driver and front passenger are also treated to sumptuous bucket seats with multiple power adjustments and heating/cooling.

Up to three passengers can share the rear bench seat and indulge in the luxury of three-zone automatic climate control, heating for the outer seating positions, privacy glass, roll-up sunshades, two USB-C ports and lots more.

The GLS450d comes standard with a 3.0-litre turbocharged inline six-cylinder diesel producing 270kW of power at 4000rpm and 750Nm of torque between 1350-2800rpm.

This is paired with a 48V mild-hybrid system comprising a 48-volt battery (charged by regenerative braking) and an integrated starter-generator which provides both seamless engine stop-start and up to 15kW/200Nm of extra power and torque during acceleration.

A nine-speed torque converter automatic provides the choice of manual shifting using the steering wheel-mounted paddles, along with several selectable drive modes.

The active all-wheel-drive system continuously adjusts the engine’s torque delivery between front and rear axles (and individual wheels as needed) to maintain optimum traction and handling.

According to BMW, the M50 xDrive features the most powerful inline six-cylinder petrol engine fitted to an M Performance model.

This 3.0-litre unit clearly benefits from BMW’s twin-scroll turbocharging technology, which combined with variable valve timing and an extra 13kW/200Nm from the 48V mild-hybrid technology produces a stomping 293kW of power at 5500rpm and 580Nm of torque at 1900rpm.

It also has a ‘boost’ function, which provides an extra burst of power for short periods when maximum acceleration is required when overtaking etc.

It’s activated by the left paddle-shifter on the steering wheel and automatically optimises transmission/chassis settings to suit. There’s also a drive mode selector, with ‘Sport’ offering the most responsive and engaging experience.

The eight-speed torque converter automatic is a refined and efficient transmission well suited to this full-time all-wheel drive application. Rapid-fire manual shifting is also available using the steering wheel paddles.

Mercedes-Benz claims official combined consumption of 7.8L/100km and the dash display was showing 9.0 when we stopped to refuel at the completion of our 368km test, which included the usual mix of suburban, city and highway driving with up to five passengers at times and light luggage.

Our own figure, calculated from fuel bowser and tripmeter readings, was close at 9.5 which is outstanding sub-10L/100km economy for such a substantial vehicle in mostly metropolitan use. Therefore, based on our own consumption figure, you could expect a real-world driving range of around 950km from its 90-litre diesel tank.

BMW claims an official average combined consumption of 8.2L/100km but the dash display was showing 9.9 at the completion of our 210km test, which included a mix of suburban, city and highway travel.

Our own figure, calculated from fuel bowser and tripmeter readings, came in slightly higher again at 10.5L/100km, which given our test vehicle’s two-tonne-plus weight and performance capabilities is still reasonable economy.

So, based on our figures, you could expect a realistic driving range of around 600km from its 65-litre tank, which prefers premium 98 RON petrol.

It’s an enjoyable vehicle to drive, with multiple power adjustments for the seat and steering wheel combined with a large left footrest which provide supreme driver comfort and support.

The powerful and responsive turbocharged six-cylinder diesel and nine-speed auto are well suited to this application. The engine’s ample torque provides spirited acceleration from standing starts, taking only six seconds to reach triple-digit speeds.

This drivetrain would be well suited to heavy towing duties, given the 48V mild-hybrid system can contribute an extra 200Nm (in addition to the engine’s 750Nm), which raises the total theoretical torque output to almost 1000Nm.

The active air suspension provides a wonderfully cushioned ride that floats over bumpy roads, while maintaining excellent handling response and surprising agility. These commendable chassis dynamics, combined with the powerful and responsive drivetrain, makes the vehicle feel smaller and lighter than its dimensions and kerb weight would suggest.

Overall, it’s difficult to fault from a driver’s perspective, with the only exception being the voice activation function. This is often triggered by words or phrases other than ‘Hey Mercedes’ resulting in regular interruption of conversations. This needs some fine tuning.

First, the fun stuff. It certainly feels like ‘the ultimate driving machine’ when you slide behind the chunky leather-rimmed flat-bottom steering wheel and hold it in your hands.

The driver’s seat offers not only powered adjustment of backrest and base-cushion rake, but also four-way lumbar support and side-bolsters that can tighten their embrace of your upper torso to contend with high cornering loads.

There’s also manual extension of the base-cushion length for greater thigh support and a big left footrest to brace against, so you could not ask for a more accommodating and purposeful driving position.

The steering is perfectly weighted and the quartet of enormous disc brakes provide ample bite with superb pedal feel. Combined with its adaptive suspension and wide grippy tyres, the X3 is a family car that’s also invigorating to drive, particularly when you select the ‘Sport’ mode.

The enhanced engine response and sharper steering that result (even the instrument panel display changes) make any twisting mountain road an engaging experience, enhanced by an intoxicating exhaust note that only a BMW M six can deliver.

The turbocharged engine offers an unyielding surge of acceleration from well below peak torque at 1900rpm to maximum power at 5500rpm, making BMW’s claim of 0-100km/h in a scant 4.6 seconds sound credible.

You can also manually change gears using the steering wheel paddles, but we found the gearing and shift calibrations so good that we preferred to leave it in auto mode.

However, the X3 M50 has two distinct personalities, as in more relaxed drive modes it’s just as happy serving as practical family transport during the week for grocery shopping, daily school runs and other common tasks.

It’s also a comfortable tourer for family getaways, with long gearing that requires only 1500rpm to cruise at 100km/h where low engine, tyre and wind noise allow highway conversations at lounge room levels.

No ANCAP rating as yet but this X3 comes with a long menu of standard safety features including multiple airbags, AEB with pedestrian/cyclist/junction detection, front collision warning with brake intervention, lane-keeping, active cruise control, head-up display with speed sign recognition, front and rear cross-traffic alert, tyre pressure monitoring and lots more.

There are also ISOFIX and top tethers for the two outer rear seating positions.

The GLS comes with a five-years/unlimited km warranty (better than BMW and Lexus) and five years of roadside assistance. Scheduled servicing is every 12 months/25,000km whichever occurs first.

Mercedes-Benz offers capped-price pre-paid servicing packages with three, four or five-year terms. For example, the total upfront cost of the minimum three-year term is $4090, or an average of $1363 per service.

It comes standard with a five-year, unlimited km warranty.

Scheduled servicing is determined by BMW’s vehicle monitoring system which advises when a service is needed, typically around 12 months/15,000km.

A capped-price servicing package covering five years/80,000km (whichever occurs first) totals $2475, or an average of $495 per service.