BMW 4 Series vs Mercedes-Benz E400

What's the difference?

The BMW M440i xDrive Gran Coupe manages to combine sleek design with a fun-to-drive personality and surprising practicality. It’s a rapid premium, four-door, five-seater offering extra flair, and in this part of the market, good value. But more than anything else it’s got a cracking in-line six under the bonnet.

A convertible that doesn't feel like one when the roof is in place is no easy task to build, but it's one Merc's engineers have pulled off with the E400 4Matic Cabriolet. Effortless power, a tonne of technology and a comfy, leather-wrapped cabin all make Merc's drop-top E-Class a strong proposition.

So, how does this four-door 4 Series differ from a four-door 3 Series? The answer is as plain as the nose on this car’s face.

BMW’s head of design, Adrian van Hooydonk, has been expanding the brand’s signature ‘kidney grille’ in every conceivable direction, and this is the much talked about interpretation adorning all 4 Series models (petrol, hybrid and electric) as well as the M3 sedan.

The new Gran Coupe is longer, wider, and taller than the outgoing model, and the track is broader, front and rear. The wheelbase has also been extended, now a whole 5.0mm longer than the 3 Series.

The DRLs and headlight main beams are LED with laser high beams, immense gills square up the edges of the front clip, while a vent and the strake attached to it stand the car apart. Plus, of course, the doors are frameless. 

One niggle, though. I’m not in love with the slender door handles. It’s hard to get a good grip on them, especially in the wet. 

Standard 19-inch alloy rims are shod with Pirelli P Zero rubber 245/40 fr / 255/40 rr), the roofline slopes distinctly towards the rear, a lip spoiler on the trailing edge of the tailgate is classic BMW, darkened LED tail-lights wrap around the rear corner, and a diffuser-type panel is flanked by large exhaust apertures.

Our car’s ‘Aventurine Red’ finish is a $3850 option, but to my eyes anyway it looks superb.

Exterior trim including the grille frame, front air intake inserts, mirror upper housing, model designation badges, and tailpipe are finished in ‘Cerium Grey’, which I reckon 99.9 per cent of people will see as black. 

The interior will be familiar territory for any current BMW owner, the 12.3-inch digital instrument screen sitting in a compact, hooded binnacle, and partnering with a 10.25-inch multimedia display standing proud of the dash above the broad centre stack. 

The seats are trimmed in top-shelf leather with blue contrast stitching, plus the grippy sports wheel is also wrapped in genuine hide.

BMW calls the finish on the main buttons and controls ‘Galvanic’ which translates to a slick silver metallic look and feel. Configurable ambient interior lighting is a nice touch, and the broad console enhances the driver-focused feel, with a sprinkling of carbon-fibre around the centre console and dash lifting the sense of occasion.

Overall, the interior feels clean and classy with an obvious attention to detail.  

Elegance. That's the word that springs to mind when you first clamp eyes on the E400 Cabriolet. While the Coupe version has a crouched-over sportiness about its exterior design, the convertible is all about big and boat-like proportions, especially with the fabric roof opened.

Like nearly all drop-tops, the E400 looks best with the cabin open to the elements, and the side profile especially paints a picture of well-heeled wafting, with only the AMG alloys and body styling hinting at the performance on offer under the bonnet.

Inside, expect perfectly executed modern luxury, with soft leather seats, touchpoints that melt under the fingers and a sprinkling of woodgrain trim. All of which feel like old-world luxury, nicely juxtaposed by the huge twin-screen display that dominates the dash.

At close to 4.8m long the 4 Series Gran Coupe is a sizeable machine. Up front, the feeling is airy and comfortable, and the rear is surprisingly spacious, especially in light of the car's sloping roofline.

At 183cm I have to fold myself tightly to fit under the low roof, but once inside I have enough room to sit behind the driver’s seat set for my position with more than enough legroom and adequate headroom. Put three full-size adults across the back row, though, and there will be breathing difficulties.

Kids will be fine, however, and individual vents with adjustable temp in the rear was a big plus during a particularly hot test week.

For storage there are generous door bins in the front with room for large bottles, a decent glove box, dual cupholders in the centre console, a reasonable lidded bin (which doubles as a centre armrest), and the wireless device charging bay (forward of the gearshift) makes a handy oddments space when not in use.

In the rear, again the doors feature pockets with room for (medium-size) bottles, there’s a fold down centre armrest with two cupholders, but thanks to the one-piece shells on our test car’s optional M Sport front seats there are no map pockets.

Power and connectivity runs to a USB-A socket and a 12V outlet in the front centre console, as well a USB-C port in the front storage bin, a pair of USB-Cs in the rear, and a 12V outlet in the boot.

Speaking of which, lift the tailgate and with the rear seat upright we were able to fit all three of our suitcases or the beefy CarsGuide pram into the healthy 470-litre (VDA) boot space.

Lower the 40/20/40 split-folding rear seat down and 1290 litres of volume is at your disposal. Plus there are handy bag hooks and tie-down anchors to help secure loose loads.

You can also tow a braked trailer up to 1.8 tonnes (750kg unbraked), but don’t bother looking for a spare of any description, a repair/inflator kit is your only option.

It's a two-door, four-seat convertible, so practicality isn't at the very top of its list of strengths.

That said, life is peachy for upfront riders, both of whom will travel in spacious luxury. There are two cupholders hidden beneath a woodgrain cover underneath the climate controls - also home to a power outlet - as well as a clever double-hinged central storage bin that can be opened by either the passenger or driver, and which opens to reveal two USB points.

There's room in the doors for bottles, too, and the entertainment system can be controlled via a touchpad controller mounted above the traditional click wheel - although, to be honest, using it is harder and more time consuming than simply pretending it doesn't exist.

Climbing into the back (and we mean climb - there are no rear doors) is made easier by the fact you can fold and slide the front seats automatically by pulling a lever mounted near the headrest. Once there, though, you'll find space is a little tighter, and you feel weirdly cocooned, owing to the huge raised tunnel that runs through the middle of the cabin, and the low roof line.

There are two cupholders that live in the space where the middle seat would normally go, and there's a little bottle-holder cubby to the left of both backseat riders. There are air vents back there, too, but no temperature controls.

The front doors are huge and really very heavy, requiring considerable heft to open them.

The boot space is predictably a little limited, with 385 litres on offer. There's also a little flip-down separator, which shows you how much room the roof will need to come down, reducing boot space to 310 litres. Speaking of which, the soft-top can be lowered in just 20 seconds, and at speeds up to 50km/h.

One practicality quirk, though. The front (and only) doors are huge and really very heavy, requiring considerable heft to open them, especially if you're parked on a slight angle. Honestly, I was reduced to kind of pushing them open with my foot at times.

At $157,400, the Cabriolet is the most expensive model in the E400 family, and is roughly $20k more than the sedan and $10k more than the coupe variants.

That money buys you a comprehensively kitted-out ride - as it really should - with the E400 Cabriolet arriving with 20-inch AMG alloys, LED headlights (made up of 84 LEDs) with high-beam assist, proximity unlocking with push-button start, air suspension and Merc's AIRCAP - a lip above the windscreen that's designed to push air up and over the cabin when the roof is down.

Inside, you'll find leather seats, dual-zone climate control and the clever 'AirScarf' system, which pumps hot air onto your neck when the roof is down (and it's cold out). You'll also nab heated front seats, power windows front and back and an automatic belt feeder, which saves you reaching over your shoulder to get to your seatbelt. So exhausting.

On the tech front, expect a killer 590W, 13-speaker Burmester stereo, controlled by the seriously impressive widescreen cockpit; two 12.3-inch screens that spill from about the centre of the dash all the way to the driver's binnacle, and control everything from navigation to Apple CarPlay and Android Auto.

There's a whole bunch of safety stuff, including semi-autonomous technology, but we'll drill down on that under the Safety sub-heading.

Under the bonnet is BMW’s (B58) all-alloy 3.0-litre twin-scroll turbo intercooled, in-line six-cylinder engine, driving all four wheels via an eight-speed automatic transmission and electronically controlled clutch pack, as well as an electronic limited-slip differential at the rear.

It features high-pressure direct-injection and BMW’s ‘Valvetronic’ system managing air flow to the intake side, to produce 285kW at a relatively high 5800-6500rpm. But the big punch is 500Nm of peak torque from just 1900rpm all the way to 5000rpm.

The M440i is also a mild-hybrid with a 48-volt starter motor-generator and supplementary battery able to give an 8.0kW kick at low engine speeds.

It's a fabulous engine, this twin-turbocharged V6 - even if it doesn't feel quite so lively in Cabriolet form as it does in the hardtop equivalents.

The 3.0-litre unit produces 245kW/480Nm, sending it to all four wheels via a nine-speed automatic transmission, linked to the standard 4Matic all-wheel drive system.

BMW’s official fuel economy figure for the M440i xDrive Gran Coupe, on the ADR 81/02 - urban, extra-urban cycle, is 8.2L/100km, the 3.0-litre turbo six-cylinder emitting 187g/km of C02 in the process.

Stop/start is standard, and we saw an average of 11.1L/100km over city, B-road and freeway running during a week with the car.

With the 59-litre tank brimmed (with minimum 95RON premium unleaded) that real-world test number translates to a range of around 530km.  

Mercedes claims 7.4L/100km on the combined cycle (but you can expect to be pushing nine litres in real-world conditions), with emissions pegged at 170g per kilometre of CO2.

The 66-litre tank will only accepts 95RON fuel.

BMW says the M440i xDrive Gran Coupe will accelerate from 0-100km/h in 4.7sec, and I reckon the threshold for a properly quick car is sub-five seconds.

The 3.0-litre turbo six develops its peak power of 285kW between a relatively lofty 5800-6500rpm, but the big number is a solid 500Nm punch of pulling power delivered between 1900-5000rpm.

Squeeze the throttle pedal pretty much anywhere in the rev range and the response is glorious. Rapid acceleration accompanied by raucous engine noise and rorty exhaust note (albeit with some synthetic support). Various pops and bangs in the Sport settings add extra entertainment.. 

The eight-speed auto gets some electric support from the mild-hybrid system to fill the torque gap on up shifts, and the result is a conventional torque-converter transmission that behaves like a dual-clutch.

Shifts are seamless in general driving, and satisfyingly quick in a more aggressive mode, the wheel-mounted paddles dialing up the fun in manual changes. 

Suspension is double wishbone front and multi-link rear with the standard ‘Adaptive M Suspension’ built around an adaptive damper set-up.

The change between the ‘Comfort’ setting to the ‘Sport’ or ‘Sport+’ calibration is close to instant and makes a discernible difference, especially in terms of ride comfort.

I found the best ‘Individual Sport’ arrangement to be damping in Comfort, with the steering engine and transmission in Sport. The car flows so beautifully through corners with urgent response from the powertrain.

By all means dial up the suspension if you’re having a real crack, but the car feels superbly balanced, stable and predictable in Comfort (front to rear weight distribution is 50:50).

The electrically-assisted variable-ratio steering is nicely weighted with good road feel, and the grippy sports steering wheel is a nice point of contact.

The xDrive AWD system’s default setting is rear-biased, although it will push most of the drive forward when required. But the RWD feel is unmistakable. 

The M440i weighs in at around 1.9 tonnes but feels lighter and more nimble than that figure would typically indicate.  

A standard electronically-controlled M Sport limited-slip differential puts the power down confidently. I have a favourite LSD test corner on my regular evaluation drive, a sharply twisting and rising left-hander.

Rolling into it in a low gear before planting the throttle mid-corner, the car simply hunkers down without a hint of fuss (or traction loss) as it rockets out the other side.

Optional M Sport front seats ($2000) provide comfort and firm location in equal measure and in terms of ergonomics BMW knows how to focus on the driver and set-up an efficient environment. Key controls are perfectly positioned and simple to operate.

I have an issue with the ‘Lane Departure Warning’ function, however, which is too quick to intervene and overly intrusive when it does so. I turned the ‘Steering Intervention’ function off. You can dial down steering wheel vibration warnings, too.

The standard M Sport brakes feature big vented rotors front and rear, with fixed four-piston front calipers doing the bulk of the work. They’re strong but don’t bite or release too aggressively. It’s easy to grease in a smooth application. 

Sure, the E400 Cabriolet can drive itself, but we’re equally pleased to note that it’s still a lot more fun handling the steering duties yourself.

And that is mostly due to that fabulous engine; quiet and effortless at city speeds, rorty and enthusiastic at pace, and genuinely angry with the drive setting switched to their most hardcore Sport+ mode.

We’ve already spent time in the sedan version, and while this Cabriolet is heavier (1935kg vs 1820kg) and slightly slower to 100km/h (5.5sec vs 5.2sec) it doesn’t immediately feel it behind the wheel, with a similar and satisfying lurch into the future when you plant your foot.

But hard charging is not what this car is about, and the E 400 is at its peachy best when rolling about the city or the ‘burbs with the top down, and the warm summer air washing through the cabin.

In its normal drive settings, the steering is light but engaged, and the ride on offer from the standard air suspension is outstanding, cosseting the cabin from all but the very worst road imperfections, while the torque from the V6 serves up effortless, unobtrusive acceleration.

With the roof up, Merc’s designers have done a stellar job of hiding the fact this thing is a convertible at all. It’s a solid-feeling cabin with the fabric roof fastened, and the cabin is quiet and free from wind noise.

There are few cars on the road as overloaded with safety technology as the E400 Cabriolet.

The standard stuff is all there, of course. There's a 360-degree parking camera, as well as nine airbags (dual front, dual pelvic/thorax for front-seat passengers, dual sidebags for rear passengers, dual head bags in the doors and a knee airbag for the driver), rollover protection and tyre-pressure monitoring, as well as braking and traction aids.

But the E400 adds some really clever technology, including Merc's Driving Assistance Package Plus, which adds active lane keeping, blind-spot assist, cross-traffic alert and evasive steering assist.

It's this suite of systems that allows the E400 to navigate freeways autonomously, including changing lanes on demand. At the moment, the system will warn you to keep your hands on the wheel every so often, but you can sense a time when that will no longer be required. And that time is soon.

The E-Class range scored the maximum five-star ANCAP safety rating when crash tested in 2016.

The M440i Gran Coupe is covered by BMW’s three-year/unlimited km warranty (including paintwork), as well as 12-year/unlimited km anti-corrosion (perforation) cover. 

That’s off the premium market pace now with Genesis, Jaguar, and Mercedes-Benz at five years/unlimited km and Lexus set to join them from January 1st, 2022. 

That said, roadside assistance is provided for the duration of the main warranty, but it’s worth noting “rattles and squeaks” are only covered for one year.

Service is condition-based, the car telling you when maintenance is required, and a range of service packages are available. The basic plan covering a 4 Series for five years/80,000km comes in at $1750. 

Expect the usual three-year, unlimited-kilometre warranty, with service intervals pegged at 12 months or 25,000km. Mercedes' capped-price servicing scheme limits maintenance costs to $2280 for the first three years of ownership.