Mercedes-Benz S300 vs MG Im5

What's the difference?

The 2018 Mercedes-Benz S-Class remains a technological tour de force, a luxury sedan to be reckoned with - one that has safety, technology, comfort, finesse and performance all rolled into a stylish package. 

It's hard to see why you'd need anything more than the S 350 d, which is now much more attractively priced. It'd be my pick, but I'd have to get the Energizing Comfort Control package, and probably the AMG styling pack, too. And even then it would cost less than its predecessor.

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.

I swear it has been facelifted, and the changes are bigger than they might appear. There is no doubt that the S-Class shape is largely unchanged, but the German company has kept the modifications minimal in the scheme of things.

That doesn’t mean those changes are unnecessary, though. The new headlights, for example, are standard on every model, and are constructed with 84 LEDs (including three for the daytime running lights), and of course they’re adaptive with automated high-beam - meaning they’ll shield other road users from the glare of the lights at night. And the lights themselves will throw a main beam up to 650 metres, according to the company. 

Other things are slightly more cosmetic, like the revised three-bar grille treatment, new front and rear bumper designs that feature broader sculpted sections to widen the stance of the car, and there are new LED tail-lights as well.

The smallest set of wheels used to consist of 18-inch rims, but now the base car rolls on 19s, while the rest of the expansive range sits on 20s. 

The inside has seen some changes, too, but the appearance of things in the cabin isn’t the focal point - its the usability of the technology that's the big change. 

Oh, but I should tell you there are now 64 ambient lighting colours to choose from, which is up from seven, and now you can also set the lighting in three different zones - so theoretically you can have blue, orange and green areas of the cockpit, if you’re gross.

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.

If you’re buying a Mercedes-Benz S-Class there’s a good chance you’re more interested in the back seat than the front: you could be buying it for a business, or you could like to be driven around - and there are definitely worse places you could be.

We would suggest, though, that the best place you could be if that’s your caper is in the back of a long-wheelbase S-Class model, which has extra legroom. 

And if you happen to be in a LWB model with the 'Business Class Package', you’ll enjoy two individual rear seats rather than a three-seat bench, folding tables for your bento box or laptop, and an ‘executive seat’ on the passenger side that features a foot rest and allows you to slide the front seat forward to liberate more room. Deluxe. 

No matter if you are in one of the stretched models demarcated as such by the ‘L’ suffix or not, you will enjoy excellent seat comfort and good head- and shoulder-room. Legroom in the regular models isn’t as plentiful as you might expect: much more affordable cars like the Hyundai Sonata give the S-Class a run for its money in that regard.

There are good storage options for odds and ends, with the back seat featuring a fold-down armrest with pop-out cupholders and a storage box, as well as map pockets - and the boot space varies depending on the model, but the S 350 d has a 510-litre cargo capacity (VDA). All four doors have bottle holsters, and a bit of extra room besides. Of course there are rear-seat air-vents, and if you’re kids are lucky enough to ride around in a S-Class, the two ISOFIX/three top-tether points will be welcome.

Up front there are two cupholders between the seats, and a new wireless phone charger in the centre console (Qi compatible phones only). There are two USB ports as standard in most models, while models with the rear seat entertainment package fitted get rear USBs. 

The huge screen that runs across two-thirds of the dashboard has seen the noticeable join marker removed for this update, with the monitors being upgraded to a higher resolution and the graphics have been reworked, too. The codpiece-style controller of the Comand media interface remains, and while it still isn’t as simple as other controllers, it is reasonably easy to get used to. 

So … what about Beyonce? 

She comes in as part of the Energizing Comfort Control system, which is standard in some models and a $1400 option in those that don’t have it fitted. 

Essentially it allows you to choose between different set moods: 'Joy', 'Freshness', 'Vitality', 'Warmth', 'Comfort' and 'Training', the latter of which offers three different stretching/exercise programs that last for 10 minutes to stop fatigue. The instructions are given by voice over the sound system.

Each of the moods will adjust the temperature and ventilation (the Freshness setting offers ‘gusts’ of fresh air as if you’re at the beach!), ambient lighting, air fragrance and intensity, and the massage function for the seats. And the music bit - there are predefined songs the system can cue up to suit the mood, or it can identify songs on a hard-drive or USB that suit the programs by analysing the tempo of the tune. Amazing, right?

The new steering wheel looks a lot sportier than the one in the pre-update car, and it has finally done away with the awkward cruise control stalk in favour of steering wheel buttons for the adaptive cruise control system.

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.

The big news for the majority of S-Class buyers is the new engine in the S 350d, which is a 2.9-litre in-line six-cylinder turbo-diesel with 210kW of power and 600Nm of torque. It has a nine-speed automatic and is rear-wheel drive (RWD).

That same diesel engine is wicked up in the S 400d L, with that model churning out 250kW and 700Nm, and remains rear-drive with a nine-speed auto.

The petrol model range is opened by the S 450 L with a 3.0-litre six-cylinder twin-turbo mill producing 270kW/520Nm. Again, nine-speed auto, RWD.

The S 560 and S 560L run the same 4.0-litre twin-turbo V8 petrol with 345kW of power and 700Nm of torque. Nine-speed auto, rear-drive - naturally!

The AMG-fettled S 63 has a thumping twin-turbo 4.0-litre V8 petrol engine with 450kW and 900Nm, with a nine-speed MCT multi-clutch auto and - you guessed it - RWD.

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.

The diesel models are - unsurprisingly - the most frugal in the range, with the entry-level S 350 d using a claimed 5.4 litres per 100km across a range of disciplines.

The S 400 d L - which uses a higher-output version of the same diesel drivetrain as the model above - uses only a minuscule amount more: its claim is 5.5L/100km. 

The most frugal of the petrols is the S 450 L, with its six-pot petrol twin-turbo using a claimed 8.4L/100km.

Every model has stop-start - including the AMG - and the V8 petrols also feature cylinder deactivation when in 'Eco' mode.

That cylinder deactivation system helps the S 560 achieve an incredibly low claimed consumption of 8.5L/100km. So does the longer, slightly heavier S 560 L.

The higher-out Mercedes-AMG S 63 L uses 9.0L/100km, according to its claim. Amazing for the outputs of the engine.

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. 

Smooth. It wasn’t even because I’d chosen the Energizing Comfort Control mood to elicit that vibe. It’s smooth - and so it should be.

Whether it’s the near-silent new six-cylinder diesel, which hauls the near two-tonne sedan along with less fuss than a medical centre receptionist dealing with a room full of coughing patients. There is no fuss. You just hand over control to the engine, and trust it will get you where you need to be.

The V8 petrol in the S 560 also has a bit of a silent killer vibe to it. There’s perhaps not as much noise as a V8 fan might want, but the mumbo is there, and in both cars the gearshifts are sublimely timed and super smooth.

Admittedly, the stiff-sided run-flat tyres on both the 19- and 20-inch wheels can exhibit a slight terseness over sharp edges, but when it comes to rolling over pockmarked surfaces or rougher country backroads, the ride offered up by the air suspension with variable dampers is superb. Put it in Sport mode and it stiffens up to the degree you’d expect, but Comfort is no doubt the best place to be.

The steering is super light but accurate, meaning it’s easier than you’d think to pilot this behemoth of a sedan through corners. The grip on offer is excellent, too, even if traction can be an issue - I had a full couple of seconds of strobe light action from the traction control light when I buried the throttle in the S 560. 

I didn’t get a chance to drive the six-cylinder petrol S 450 L, or the S 400 d L. And, I’m really sad to report, there was no opportunity to drive the AMG S 63 L, either. 

But the overall feeling of the updated range is that it remains a deluxe and delightful limousine - whether you have the good fortune of being in the driver’s seat or not.

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.

Mercedes-Benz offers a standard three-year/unlimited kilometre warranty.

Servicing is due every 12 months or 25,000km on all engines except AMG drivetrains, which require servicing every year or 20,000km. 

Mercedes-Benz has a (pricey!) capped-price servicing plan. The standard diesel and petrol models in the S-Class range cost $596 for the first service, and $1192 for the second and third visits. The costs for the sole AMG model is $736 for the first service, then the second and third visits are $1472 per.

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.