If imitation is the sincerest form of flattery, Mercedes must be feeling rather good about itself. It was the first company to create a four-door luxury coupe – with the CLS in 2005 – and its rivals have been scrabbling to follow suit ever since.
The latest to join the pack is BMW. Its 6 Series Gran Coupe arrives this month, from £61,390. The four-door is essentially a stretched version of the 6 Series Coupe, and straddles the 5 Series and 7 Series line-ups in BMW’s busy range. It’s available with a pair of six-cylinder engines from launch, and here we test the £63,900 640d SE.
Having started the four-door premium coupe sector all that time ago, the CLS has the advantage of being one step ahead of the competition. It’s now in its second generation, and offers head-turning looks, a broad engine range and sharper dynamics than its predecessor. We’ve chosen the mid-range CLS 350 CDI Sport, priced at £54,210.
Completing our test trio is the Porsche Panamera. It sets the standard for driving thrills in this class, plus in £62,134 diesel guise it should be affordable to run.
All three cars are stylish alternatives to the conventional premium saloon – but in a market where design is king, which is the best all-round package?
Mercedes CLS 350 CDI
If BMW wants to gain the upper hand in the increasingly busy four-door coupe market, this is the car it will have to beat. The Mercedes CLS is now in its second evolution, and builds on the strengths of its predecessor, which proved a surprise hit for the brand first time around.
Based on the platform and running gear of the E-Class saloon, the CLS is a more complex package than its predecessor. If you loved the original for its clean, flowing lines, there’s a chance that the current version’s bulges and sharp edges may leave you cold. When parked alongside the 6 Series Gran Coupe during our test, certain elements did look a little fussy.
With the exception of a few minor styling tweaks the cabin is carried over from the E-Class saloon, which is no bad thing. The seats are comfortable – and ours came with the £1,310 option of dynamic bolsters which hold you in when cornering – while the column-mounted gearshift is easy to live with and frees up space for the intuitive COMAND infotainment control system.
In an effort to distance it from the E-Class, Mercedes offers the CLS only with seating for two in the back. Although this means each rear occupant gets a more sculpted chair, the oversized armrest that runs the full length of the car confines passengers’ legs strictly to the area behind the front seats. This, combined with the low roofline and chunky door furniture, means that six-footers will find the back of the car rather cramped.
Another area where the CLS disappoints is quality. Overall the cabin feels solid and upmarket, but some elements of the dash trim – notably the rotary controls for the heating – seem disappointingly cheap. On the plus side, the CLS boasts the biggest boot of our test trio with a volume of 520 litres.
Unlike BMW, Mercedes doesn’t reserve special engine options solely for the CLS range. The 265bhp 3.0-litre CDI diesel and standard seven-speed automatic box will be familiar to owners of other Mercedes, and the car proves a fair match for the more powerful BMW, recording a 0-60mph time that’s only half-a-second slower. It also feels quicker and more eager to accelerate than the Gran Coupe, particularly from low speeds.
Away from the track, our CLS didn’t seem quite as sharp as its rivals. It’s composed and capable through a series of turns, but the steering feels over-assisted, particularly at low speeds. And despite our car’s £1,500 optional air-suspension, the ride wasn’t quite as supple as the smooth BMW’s.
However, the Mercedes looks something of a bargain against the competition here. Even after you’ve added creature comforts such as air-suspension, dynamic massage seats and upgraded leather trim, you’ll still be paying thousands less than you would for the BMW or Porsche.
So while the CLS isn’t perfect, with such a significant price advantage it’s easy to overlook the car’s few failings.
BMW 640d Gran Coupe
It’s difficult to explain exactly why the BMW 6 Series Gran Coupe exists. As its name suggests, the newcomer is a four-door version of the 6 Series coupe. And that, in turn, is a two-door version of the 5 Series, which already has a sporty spin-off in the form of the Gran Turismo.
Yet despite its mangled family tree, the 6 Series Gran Coupe has a coherence and grace to its styling that we haven’t seen from the brand for some years. Although the front end doesn’t quite have the visual impact you’d expect, the flowing roofline, chiselled shoulders and tapered tail all gel together beautifully.
The car is also packed with clever and evocative details. Pull the rear door open and a sleek Gran Coupe logo is revealed in the shut panel next to the car’s trademark Hofmeister kink C-pillar. Run your eye along the front wing and you’ll spot an elegant chrome flash which harks back to classic BMW coupes and roadsters of the fifties.
The designers also get top marks for the interior layout, which combines high-end luxury with a raft of clever gadgets. The first thing that strikes you is the vast display that sits on top of the dashboard. As wide as the screen on a laptop, it dominates the front of the cabin and delivers crisp graphics which make easy work of navigating the 640’s countless features.
The BMW also scores for cabin space. Head and legroom in the front are predictably generous, but it’s in the back where the Gran Coupe really impresses. By extending the wheelbase by 113mm, carving out the door panels and stretching the seat bench the full width of the car, BMW has created a far more inviting space for those confined to the rear.
There are, however, a couple of features that don’t quite work. The operation of the gearshift is blighted by a clumsy unlock button and a rocker-style selection mechanism that feels far from intuitive. Instead of sliding the lever back until you reach the desired gear, you have to pull or push a number of times as it scrolls through the options.
The seats also proved something of an issue during our week-long test. Even though they offer adjustment in pretty much every direction, a number of testers struggled to get comfortable on long journeys.
Thankfully, one area of the Gran Coupe that didn’t divide opinion was the drivetrain. While the engine is based on the 3.0-litre six-cylinder diesel that appears in the 7 Series, in the 6 Series it offers 10bhp more. The car also features a newer transmission: an eight-speed auto borrowed from the 5 Series range.
Despite being such a mix and match, the 640d’s drivetrain works beautifully. With deep reserves of low-range pulling power and perfectly spaced ratios, the car punches out of corners with an eagerness that belies its 1,865kg kerbweight. Plus, the box has a manual function that allows shifts via a pair of neatly fashioned steering wheel paddles, and this ensured the BMW was the only car of our test trio that felt happy letting its driver make the choices.
Thanks to its 5 Series underpinnings, the Gran Coupe also delivers when it comes to driving dynamics. It strikes a fine balance between sportiness and refinement – soaking up surface imperfections without robbing the driver of feedback from the road surface. The front end is accurate and easy to place, while the car’s agility through twisting sections of tarmac speaks volumes for BMW’s chassis know-how.
But if we have a criticism of the Gran Coupe, it has to be value for money. With a basic price of £63,900, the 640d is the most expensive car in this test – it costs £1,766 more than the Panamera and £9,690 more than the CLS. Although the BMW does come with a generous kit list, it offers no more space or performance than its two rivals here. So while it’s an easy car to love, your devotion will be sorely tested when you’re asked to sign on the dotted line.
One thing you are guaranteed to get if you own a Panamera is attention. The five-door Porsche is taller and wider than the BMW and Mercedes, and is imposing to look at and sit in. Combining supercar-style details with brutal proportions, it’s not for those who like to blend into the background. However, in a market where sleek styling and sophistication are key factors, the Panamera doesn’t quite hit the mark.
Porsche’s desire to be different extends to the cabin, where the Panamera stands out from the crowd in a number of important ways. Given the car’s larger dimensions, the interior feels bigger and more accommodating, with a greater glass area allowing more light in. The rear seats mirror the designs of those in front, and give decent amounts of head and legroom.
Up front the seats are supportive but narrow, and while they do without gadgets like the Mercedes’ pneumatic bolstering, they proved the most comfortable of our test trio.
However, travelling in the Panamera isn’t quite as relaxing as it could be. By shunning a central control system for the car’s infotainment devices, Porsche has been forced to pebbledash the centre console and steering column with an array of buttons, sliders and dials. As a result, many are obscured by the chunky gearshift or clustered under the sat-nav screen.
Under the bonnet is a 3.0-litre diesel engine that develops 247bhp and 550Nm of torque. Sourced from the vast Audi parts bin, it serves up solid performance without ever feeling too strained. We covered 0-60mph in 6.5 seconds, although the in-gear times were no match for the muscular BMW’s.
Our testers also called into question the manual gearbox controls. Instead of paddles, the car features large rocker buttons located on the steering wheel. Not only are these fiddly to use, they defy conventional gearchange wisdom by requiring the driver to push to change up. Fortunately, one area where the Panamera does shine is chassis refinement. Although the car’s sheer bulk makes it unwieldy on narrow country roads, the steering is accurate and perfectly weighted.
The Porsche also rides surprisingly well. Adaptive dampers (which come as part of the £1,052 PASM option) deliver a firmer feel if you want a sportier set-up, while in Comfort mode the car glides across poor surfaces with ease.
With a £62,134 price tag, the Panamera undercuts the Gran Coupe and initially looks decent value for money. However, dig a little deeper and you’ll soon discover that the list of standard equipment is far from generous. For starters, there are those expensive adaptive dampers, while the arch-filling 20-inch wheels fitted to our test car will set you back a further £2,249. Even a rear wiper – pretty essential on a car with a hatchback tailgate – adds £235 to the total. Factor these in, and the case for the Panamera isn’t quite so solid.