Mercedes-Benz E-Class Cabriolet E400 review

Mercedes has a change of heart and offers us a big petrol engine in the latest E-Class Cabriolet. Is the E400 worth your consideration? Jonathan Crouch reports.

Ten Second Review

The Mercedes E400 Cabriolet is, despite its relaxed, old-school vibe, a Mercedes of the modern era. It eschews a big V8 engine in favour of a more efficient twin-turbo V6 and automatically positions itself as the pick of the range.


Why would you buy a big four-seat convertible? On the face of it they make very little sense. They're more expensive than their coupe counterparts, you're at the mercy of any Stanley knife-wielding lowlife wherever you park the thing on a night out and you'll forever be trumped in the style stakes by the owner of a two-seat roadster. But perhaps herein lies the point of these cars. They don't seem to try too hard. The Mercedes-Benz E400 Cabriolet is a case in point. It's undoubtedly a very desirable consumer durable but there's a real depth of design here and it's something you wouldn't normally expect to find in a car of this genre; typically they're designed to look elegant and can let the fine details slip a bit. This big Benz has an obsessive compulsion about the details. In other words it's a car for the clinical perfectionist who wants to hint at a certain hedonistic side.

Driving Experience

There's a general rule of thumb with convertible cars that will usually see you straight. Buy the one with the biggest petrol engine you can afford. The reason? These cars usually cover fairly low mileages and are all about sensation and emotion; two subjective issues for sure, but issues that are nonetheless unlikely to be fulfilled listening to the chug of a diesel engine up front. The Mercedes E400 Cabriolet features the biggest petrol engine in the E-Class Cabriolet range. No it's not powered by a purring V8, but the smooth 3.0-litre twin-turbo V6 isn't a bad substitute and with 328bhp on tap, it's hardly slow. In fact it's downright rapid, getting to 60mph in five seconds flat before running to an electronically limited 155mph. There's a choice between a seven-speed automatic and a six-speed manual, but it's not really much of a choice all. Putting a manual gearbox in this car makes about as much sense as asking for an automatic in a Caterham 7. Instead you'll feel much better with the admittedly somewhat dull-witted seven speed self-shifter. Likewise choosing the AMG Sport trim with its firmer suspension seems to be an exercise in missing the point. The acoustic fabric roof takes a relatively leisurely twenty seconds to do its thing but it's very quiet at motorway speeds with the hood up.

Design and Build

Without wishing to pander too far to the superficial, it virtually defeats the object of a cabriolet car if it doesn't look good. Fortunately the latest E-Class does. Now that the more angular design theme of this E-Class has bedded itself in nicely, Mercedes has taken to refining the detailing and giving the car a more cohesive look. The old car's four separate lights have been replaced by a pair of elegant one-piece headlamp units. Mercedes deemed the four-eyed look to be one of the E-Class' design staples though and have replicated that with separate LED elements within the light pods. Partial LED lights come as standard, but the optional full LED system is not only better looking but incorporates a jaw-dropping host of adaptive lighting tricks. One special benefit of this E-Class Cabriolet is that, thanks to the acoustic soft top with its particularly high-grade insulation, the vehicle has the lowest noise level in its class. The interior has been tastefully developed, with better quality upholstery, and a two-part trim which stretches across the entire dashboard. It can be selected in a wood or aluminium look, irrespective of the equipment line. You'll also notice a three-clock instrument cluster, the trapezoid-shaped, high-gloss framed display in the head unit with flat-frame look, the design of the air vents as well as an analogue clock between the two central air vents. The centre console is extremely tidy with a small controller to operate the COMAND system and no gear lever.

Market and Model

Does around £50,000 strike you as good value for this car? It's tough to know what to compare it to. There's certainly much more room in one and a far more comfortable ride than you'd get in a similarly powerful Audi S5 Cabriolet, a car that adds all-wheel drive and costs around £3,000 less. So we aren't really comparing apples with apples there. BMW's 6 Series Convertible costs a lot more and offers less space. Jaguar, Lexus? Nope. There's really nothing quite like this E400 cabriolet. Four seat capability, a drop top and this sort of comfort? The Mercedes is the go-to choice. To improve comfort further, the speed-dependent AIRCAP system is offered as standard equipment. This reduces wind swirl within the vehicle interior and therefore noise levels too. The AIRCAP system deploys automatically at speeds exceeding 25 mph and the wind deflector in the front windscreen frame automatically retracts again below 9 mph. This ensures that the E-Class Cabriolet looks clean and elegant when driving slowly and when stationary. The draught-stop between the rear head restraints responds to the number of vehicle occupants with passengers in the rear detected if the seat belts are in use. The positions of the extendable wind deflector in the windscreen frame and the draught-stop are then adjusted accordingly.

Cost of Ownership

Surely the big catch to owning the most powerful petrol engine in the product range is the sting in the pocket from running costs? Well only up to a point. It always used to be the case that if you bought a decently-sized petrol unit, you were guaranteeing yourself depreciation that would be eye-watering. That's no longer the case, thanks in no small part to the improved efficiency of such engines. The E400 Cabriolet returns economy of 35.8mpg on the combined cycle and emits just 185g/km of carbon dioxide. This, I must remind you, from a sizeable car that gets to 60mph from rest in five seconds flat. Yes, you can buy diesel E-Class drop tops that get even better figures than this, but would you? Here you're getting a car where the engine suits the image of the vehicle. This probably isn't going to be a household's first car and possibly isn't going to be a second car, so outright financial rectitude isn't going to be an overarching priority. It's a luxury good and if you're going to spend the money on a car like this, spend it on the right one.


The Mercedes E400 Cabriolet is that rarity amongst modern cars. It's a vehicle that's entirely comfortable in its own skin, yet is anything but a complacent piece of product development. Cars in this class tend to have an easy life, so it would be understandable if Mercedes had soft-pedalled a little on this one, but all of the absolutely forensic attention to detail that the three-pointed star pours into its other vehicles is evident here. The 3.0-litre twin-turbo engine might have enough about it to catapult the E400 to 60mph in five seconds flat, but you'll still enjoy the same economy figures that a mid-range 2.0-litre hatch would have given you not so very long ago and the 185g/km emissions figure also looks like that of a far smaller vehicle. So here's something that's smooth, assured, handsome, beautifully built and which - as long as you specify it correctly - rides as it should. It's not cheap but other than that, it's distinctly short on caveats.

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