Mercedes-Benz Gls450 vs MG Im5

What's the difference?

The new GLS is everything you’d expect of a Mercedes-Benz with an S in its name. Luxury, performance, space, and in this case, thoughtful practicality. A super-capable, super-sized family truckster with the lot.

The MG IM5 Performance is fast, comfortable, quiet and super refined. Putting some minor spec and active safety niggles to one side, it offers the features, tech and price to match it with its well-credentialled and already popular mid-size EV sedan competitors. Is there room for one more? We think there should be.

Launched globally in mid-2019, Merc describes the GLS as the S-Class of SUVs, which is apt given its 5.2m length, 2.5-tonne mass, and ultra-premium specification.

As mentioned, the GLS is big; a step up from the already substantial model it replaces. Built with the US market in mind, in fact it’s produced in Tuscaloosa, Alabama, it’s more than five metres long, close to two metres wide, and over 1.8m tall. And there’s more than three metres between the axles, a 60mm wheelbase increase over the previous model.

And despite the size of the canvas, the Benz design team has managed to make the GLS look like a modern Merc. Signature elements include obvious ones like the slatted grille with a couple of three-pointed stars on the nose.

But there’s also, the carefully chiselled twin ‘power dome’ bonnet, scowling LED headlights and vents to aid front brake cooling and smooth aero performance around the front of the car.

The big beast’s off-road intent is highlighted by extensions around the wheelarches, with big optional 22-inch rims sitting underneath. The fact they look right-sized for the car speaks volumes about its scale.

The racy AMG Line package is standard, and a recess and pronounced character line, tightening the lower waistline is a familiar Merc treatment, plus alloy roof rails toughen the look while dialling up practicality.

The rear is relatively simple, borderline generic, with tapered tail-lights offering the only strong whiff of design personality. But believe it or not, thanks to careful detail sculpting of the body, and smoothing underneath the car it boasts a drag figure of Cd 0.32. Outstanding aero performance for a large SUV.

The driver and front passenger are presented with a sweeping dashboard dominated by twin 12.3-inch digital screens, one primarily covering the instruments, and the central screen managing the MBUX media system, including audio, nav, phone integration, car set-up, and more, plus ‘Hey Mercedes’ voice control.

The overall feel is simple, and restrained, yet massively confident, with a subtle colour palette, large squared-off elements defined by brushed metal finishes, and an obvious, intense attention to detail, from the haptic controls to the beautifully finished, multi-function steering wheel.

And the standard Burmester audio system includes a two-way in-car communication function that subtly amplifies the driver and front passenger’s voices for those in the third row, and vice versa. Sheer genius.

Playing spot the straight line on the outside of the MG IM5 is like an automotive design version of Where’s Wally? There aren’t many, in the midst of an unrelentingly curvaceous exterior treatment.

At close to five metres long and two metres wide the IM5 is appreciably longer (+211mm), a little wider (+27mm) and a bit taller (+33mm) than a Tesla Model 3. Think BMW 5 Series in terms of overall size.

And the soft-form shape is functional; the swoopy liftback boasting an ultra-slick 0.24 drag coefficient.

That said, I’m not convinced by the ‘Periscopic’ cameras informing the driver assistance systems from the front guards. They scream tacked-on afterthought. But a touch-only initial opening function for the flush door handles is cool and makes life easier.

The curves continue inside with soft-padded surfaces around the dash and doors, but the straight edge obviously came out for the 10.5-inch central media screen and vast 26.3-inch upper display. There are next to no buttons; even exterior mirror adjustment is directed from the screen to a multi-function steering wheel control.

System software (powered by a Qualcomm ‘Snapdragon’ chip) is lightning fast with a two-finger up and down swipe shortcut function on the central screen for ventilation and other functions.

The interior is light and bright thanks to the enormous panoramic sunroof. It’s been fine in cooler winter conditions during this test but it could be interesting to revisit in the heat of an Aussie summer

There are two interior colour schemes available - the ‘Highland Grey’ of our test car or ‘Dover Beige’ for those brave enough to live life with the threat of scuff marks on your shiny new car’s glamorous but vulnerably light interior.

Space is obviously a critical factor here, and no surprise there’s copious amounts of it inside the GLS.

Front seat passengers enjoy plenty of breathing room, without feeling remote from one another, and there’s lots of storage in the shape of a large lidded box/armrest between the seats, a decent glove box, two big cupholders and jumbo door pockets with room for large bottles.

There’s one data-enabled USB port in the front, two charge-ports in the second row, and four in the third row. Shouldn’t be any complaints about powering mobiles, tablets or games.

The second row feels every millimetre the SUV limo. Simply getting in and out is made easier because an auto lowering function drops the car 25mm when one of the doors is opened.

I was able to sit behind the driver’s seat set for my 183cm position with heaps of head and legroom on offer. And there’s an extra 10cm of electrically adjustable travel to play with if those in the third row agree.

The fold-down centre armrest features a lidded storage tray and twin pop-out cupholders. There are netted pockets on the front seatbacks, and again, the door bins are big enough for large drink bottles.

Three adults across the rear is a breeze, there’s climate control ventilation, and a huge glass sunroof is standard. Rather than asking ‘Are we there yet?’ the kids will be disappointed when you arrive!

Then there’s what the Cleary family refers to as ‘the way back seat.’ A pair of third row seats for the lucky kids that get to inhabit their own little world. Getting in and out is relatively civilised thanks to electric slide and tilt for the second row seats, and space is generous. I could sit comfortably, so the kids will be all smiles.

With all seats upright cargo capacity is enough for a seven-person day trip (355L VDA). Press the button to fold the 50/50 split-fold third row down and your options expand substantially (890L). And with 40/20/40 split-folding second row lowered, transportation of a full, three-ring circus is on the cards (2400L). Overall, more space than the arch enemy BMW X7.

Plus, the ability to lower the car 50mm thanks to the standard air suspension makes life even easier. And one button lowers the second and third rows at the same time.

The spare is a collapsible space-saver, and towing capacity for a braked trailer is 3500kg, with a tow ball weight of up to 140kg. The ESP system also features a trailer stabilisation function that counters oscillation with “braking intervention.”

There’s plenty of breathing room up front and in terms of storage one of the first things worth calling out are the long but relatively narrow door bins. No good for anything above unusually slender bottles, even if they’re lying down.

No conventional glove box in the dash, but there is a large lidded box (cooled and heated) between the seats that doubles as a centre armrest. It’s supplemented by a big stowage area underneath the flying buttress style centre console.  

There are two cupholders in the centre console as well as a wireless device charging pad in front of them with a vaguely phone-shaped oddments bin alongside it.  

Move to the rear and the IM5’s 75mm wheelbase advantage over the Tesla Model 3 is clear. Heaps of knee and headroom for me at 183cm sitting behind the driver’s seat set to my position. 

But… the seat sits low which pushes your knees up into the air to the point where my thighs are not contacting the seat cushion. Even though the rear seat reclines to a certain degree it’s a problem compounded by a chronic lack of room for your toes under the front seat. Awkward.

There are map pockets in the front seatbacks, modest bins in the doors and a fold-down centre armrest with two cupholders. Adjustable ventilation in the rear of the front centre console always makes life in the rear seat more pleasant.

The car also houses ‘Strong Magnets’ at various points around the cabin and boot, with a configurable adapter able to lock a phone or tablet into place for the entertainment of, in our case, back seaters. 

Speaking of devices for entertainment, there are two USB-C sockets and a 12-volt outlet in the front and another USB-C and 12V in the back, so charging isn’t an issue. 

The IM5 is a liftback so the boot aperture is generous and a capacity of 457 litres with the rear seats up is decent for a car of this size, although that’s less than the Tesla Model 3 (594L) which has an additional well under the floor. 

Still, enough room for the largest (124L) and smallest (36L) suitcases from the CarsGuide three-piece luggage set with some room to spare.

The power tailgate can be operated hands-free via the key or an always welcome under bumper kick function.

Volume expands to 1290 litres with the rear seats folded and there’s a modest 18-litre ‘frunk’ under the bonnet.

The bad news is a repair-inflator kit rather than a physical spare wheel, but the better news is the IM5 Performance can tow a 1500kg braked trailer (750kg unbraked).

The IM range also features the ‘MG iSmart’ app allowing remote control of various functions including charging, checking vehicle location and route planning. 

At $80,990, drive-away, the IM5 Performance sits at the top of a three-grade line-up that starts with a 75kWh RWD Premium model at $60,990, followed by a mid-spec 100kWh RWD Platinum for $69,990, both drive-away.

Its most prominent competitor is arguably the Tesla Model 3 Dual Motor AWD ($80,900), with others including the BYD Seal Performance AWD ($68,798), Hyundai Ioniq 6 AWD Epiq ($86,500) and Polestar 2 Long Range Dual Motor Performance ($80,380).

Worth noting, too, the IM6 range - essentially the same car with a taller SUV body - has the same model walk-up and identical pricing.

Once you’ve crossed the $80K threshold it’s fair to expect a decent basket of standard fruit and aside from the dynamic and safety features we’ll get to shortly, the IM5 Performance comes to the party.

Highlights include a double-glazed panoramic roof, power-adjustable (12-way driver, six-way passenger) heated and ventilated front seats (also heated in the rear), dual-zone climate control, 20-speaker audio (with digital radio), 256 colour ambient lighting, a power tailgate (with hands-free function) and 20-inch alloy rims.

There’s also adaptive cruise control, a heated steering wheel, wireless Android Auto and Apple CarPlay, LED headlights, keyless entry and start, wireless device charging (50W), a 10.5-inch central control screen and a sweeping 26.3-inch upper screen; the right side for instrumentation and car data, the (touch-sensitive) left side for multimedia and other onboard functions.

There’s more and it’s clear this car at least matches or betters its direct competitors for included equipment.

There are two engines on offer. The 3.0-litre (M256) in-line six-cylinder turbo-petrol GLS 450 4Matic, and the 2.9-litre (OM656) in-line six-cylinder turbo-diesel GLS 400 d 4Matic.

The all-alloy, twin-scroll single-turbo petrol engine delivers peak power of 270kW from 5500-6100rpm, and maximum torque of 500Nm across a broad plateau from 1600-4500rpm. It also features a 48-volt electrical system driving the ‘EQ Boost’ set-up, able to deliver an extra 16kW/250Nm for short periods. The integrated starter-generator also enables energy recuperation.

Although the all-alloy, twin-turbo diesel features variable valve lift it gives some ground on power, offering up 243kW between 3600-4000rpm, but torque is a solid whack, with 700Nm on tap from 1200-3000rpm. Worth noting, that to minimise emissions this engine features a “selective catalytic reduction converter” in the exhaust, which brings with it the use of an ‘AdBlue’ reducing agent. The separate AdBlue tank has a capacity of 31.6 litres.

The nine-speed auto transmission is the same in both versions, although the diesel has a slightly lower final drive ratio.

The MG IM5 Performance is powered by an electric motor on each axle - the rear (372kW/500Nm) more powerful than the front (200kW/300Nm), for overall outputs of 572kW (that’s close to 770hp) and 802Nm of pulling power.

The official term for that amount of grunt is… a lot. And we’ll get to what it means on the road in the Driving section shortly.

Claimed fuel economy for the combined (ADR 81/02 - urban, extra-urban) cycle for the GLS 450 is 9.2L/100km, the more frugal GLS 400 d trimming that to 7.7L/100km. The petrol 450 emits 210g/km of CO2 in the process, the diesel 400d dropping that slightly to 202g/km.

Stop-start is standard, you’re looking at premium unleaded for the 450 GLS, and you’ll need 90 litres of dinosaur juice to full the tank on both models.

The MG IM5 Performance features an 800-volt electrical architecture which means the 100kWh NCM battery can accept a DC peak charge of close to 400kW.

Only snag is the highest you’ll currently find in Australia is 350kW. But even at that rate you’ll still be looking at a 30-80 per cent charge in just over 15 minutes. Maximum AC charge rate is 11kW.

Claimed range is 575km (WLTP) which is less than the Tesla Model 3 Dual Motor AWD at 629km.

Over a week of city, suburban and some freeway running we saw average energy use of 20.6kWh/100km which is on the high side for an EV of this size but maybe not for one with this kind of performance potential. 

Merc claims the GLS 450 will sprint from 0-100km/h in 6.2sec, and the 400 d in 6.3sec. Not hanging around for a 2.5 tonne mothership. But the standout is the 400 d’s torque. All 700Nm of it available from just 1200rpm to 3000rpm; right in the mid-range sweet spot.

The nine-speed auto transmission is smooth yet responsive, with paddles on the wheel for manual shifts when you want to pick the ratio. The combination of effortless grunt and the nine-speeder keeping things on the boil is an impressive one.

Suspension is by double wishbones at the front and multi-links at the rear, and while you can feel the weight in cornering, the standard Airmatic air suspension (which does away with steel springs) is superb in terms of ride comfort and body control.

We took a deep breath and pushed enthusiastically through a series of sweeping corners and the fat (285/45 fr - 325/40 rr) Continental ‘PremiumContact 6’ rubber wrapped around our car’s (optional) 22-inch rims gripped hard.

The ‘4Matic’ all-wheel drive system also seamlessly shuffles torque between the front and rear axles (theoretically up to 100 per cent in each direction).

Merc has put extra focus on body rigidity, the tuning of engine and suspension mounts, and sound absorption, and it shows. The GLS 400 d is beautifully refined on the highway. A neat touch is the car automatically lowering 15mm at motorway speeds or when ‘Sport’ mode is selected.

Steering is electromechanically assisted, and Merc says the front suspension geometry has been revised to minimise vibration through the wheel. And yes, feedback is minimal, but unfortunately so is road feel with only a general connection between your hands on the wheel and the front tyres on the bitumen.

When you’re steering a large beast like this, often with something substantial hitched to the back, you want to know braking performance is up to the task, and the GLS’s big ventilated discs all around deliver reassuringly strong stopping power, with nice, progressive pedal feel to boot.

The seats are adjustable six ways to Sunday, but beyond that they’re comfortable and supportive, even over long stints behind the wheel.

We stayed on the bitumen, because, let’s face it, that’s where this car will spend 99.9 per cent of its time, with the exceptions of the boat ramp, a ski weekend or pony club.

For those special occasions the optional ‘Off-road engineering package’ adds a low-range transfer case, inter-axle locking, hill descent control, and under body armour for more serious work.

First things first, the IM5 Performance is supercar fast. This 2.3-tonne five-seater blazes from 0-100km/h 3.2 seconds and with its dual motors combining to produce 572kW/802Nm, eye-widening performance always resides underneath your right foot.

But it’s not all about straight line speed. Ride comfort is excellent. Underpinned by an all-new platform, the IM5’s suspension is by double wishbones at the front and multi-links at the rear. But the key to its bump and rut smoothing ability is air suspension and ‘continuous control’ active damping.

Fold in double-glazing on the full-length glass roof and side windows, as well as active noise cancellation and you have a serene interior environment at any speed. Also worth noting the front seats are great; as grippy as they are comfortable.

Not only that, despite its relative heft, this mid-sizer steers well, too. Not the last word in road feel but it points accurately and the standard rear steering helps with prompt (but never jerky) cornering turn-in. Flick to ‘Sport’ mode and the IM5 is up for some enthusiastic running.

The rear wheels can turn up to 12 degrees in the opposite direction to the fronts at slow speed, which makes for a usefully tight 10-metre turning circle. But above that, at lesser angles, it adds extra stability and decisiveness in the way the car steers through even tight, twisty sections.

Rubber is top-shelf Pirelli P Zeros on 20-inch alloys (245/40 fr - 275/35 rr) and it grips hard, especially in the wet weather over much of the test period. Braking is solid, as it needs to be, with ventilated discs all around and four-piston callipers at the front. 

No adjustable regen braking but you can feel the ‘Cooperative Regenerative Brake System’ (CRBS) doing its thing when you lift off the accelerator. 

The physical rear view is modest thanks to the slope of the back window reducing its functional area for the driver to that of a 1950s VW Beetle. Even the interior rear-view mirror is tiny and folds up into a recess in the headliner if you’d prefer life without it.

But that’s where a rear camera view popping up on the upper screen display (accessed via the right-hand steering wheel click control) comes in handy. Side camera views are also available as is a 360-degree overhead view, which makes parking straightforward.

If you need more parking help there are various self-parking modes including a nifty ‘Curbside’ function that will realign the car hands-free if you’re parallel parked too far out from the kerb.

In a similar vein, a ‘Rainy Night’ mode projects left and right rear views onto the main screen using AI to enhance clarity and highlight pedestrians and cars.

Overall the ADAS (Advanced Driver Assistance Systems) are relatively unobtrusive but we found ourselves switching off the incessant overspeed chime that sounds for 10 seconds if you creep over the indicated speed limit, even when the system has misfired on the correct speed. For example, 40km/h school zones on a Sunday.

The over-zealous driver distraction warning also occasionally issued a visual and audible slap on the wrist when I was looking straight ahead. Tellingly, there’s a specific quick screen for turning both these functions off, but it kinda defeats the purpose of having them in the first place.

We also found the adaptive cruise control to be hesitant in multi-lane environments, reducing speed occasionally because the system seemingly believed a car was set to merge, when it wasn’t.

No independent ANCAP safety assessment at this point but there’s a full suite of active safety tech onboard including AEB, lane departure warning, blind spot detection, rear cross-traffic alert & braking, forward collision warning, lane-change assist, tyre pressure monitoring and heaps more. And we touch on how it all operates in the Driving section above.

There are no less than nine HD cameras, 12 ultrasonic sensors and three millimetre-wave radars on duty.

If a crash is unavoidable there are seven airbags including full-length side curtains and a front centre bag. Multi-collision brake also minimises the chances of subsequent impacts after an initial crash. There are also three top tether points and three ISOFIX child seats anchors across the second row.

All right on the pace for this part of the market and the IM5’s competitive set.

The Mercedes-Benz range is covered by a three year/unlimited km warranty, which, like Audi and BMW continues to lag behind the mainstream market where the majority of players are now at five years/unlimited km, with some at seven years.

On the upside, Mercedes-Benz ‘Road Care’ roadside assistance is included in the deal for three years.

Service is scheduled for 12 months/25,000km (whichever comes first) with pricing available on an 'Up-front' or 'Pay-as-you-go' basis.

As a guide, service pricing for the outgoing GLS is set at $2600 per service (up-front) and $3250 (PAYG), a saving of $650 a pop. Fourth and fifth services are also available for pre-purchase ($3550 and $4900).

The MG IM5 Performance is covered by a seven-year/unlimited km warranty, which is a plus, but the catch is it’s conditional on authorised dealer servicing. Go elsewhere and the term drops to a more common five years/unlimited km. The drive battery is covered for eight years/160,000km, which is the norm in the Aussie market

Servicing is required every 12 months or 20,000km with charges averaging $586 per workshop visit for the first five years, which is on the high side for an EV, even at this price point, the average bumped up by a more than $1400 doozy at year four.

MG IM models are sold (with service available) through all of MG’s 100-plus dealerships across the country, so no concerns there.