BMW M4 Convertible: Review

A two-tonne Tess like the last one or a proper open top M car? PH drives the new M4 Convertible

Driving a 431hp, rear wheel-drive drop-top through unseasonably cold and ferocious storms might not sound like an optimal solution for the first drive of the BMW M4 Convertible. Indeed, the hosts are noticeably worried by the weather.

You'll only be doing this at very slow speeds

But it's perfect.

It ensures there's plenty of time to reflect on the material improvements of the fifth-generation M3 Convertible (yes, we know, but it sort of is) every time you want to change the roof position. Yes, there's a solid 20 seconds to consider that 60kg weight-saving over the old V8 model. Holding down the 'roof' button, blood draining from your fingertip, you can consider how the speed limit of 11mph (18kph in new money) while lowering or raising the roof isn't so bad. At least you don't have to stop, right?

Just don't mention the Audi S5, which can enjoy a crazily dangerous 19mph roof change. Your finger might slip off the button with rage.

Speed matters
And cabrio owners all know, there's a certain speed that you can drive and still not get wet. For the avoidance of doubt a restricted 11mph is definitely the wrong side of this threshold. Which gives you the curious dilemma - slow down and definitely get wet, to get dry? Or speed up and get less wet, but definitely not completely dry? The choice is yours!

All launch cars fitted with excellent ceramics

Luckily there's little chance of considering spec sheets and opposition when actually driving the M4 fast. BMW's optimistic description is 'track ready', the publicity material's language is clearly aimed less at the likely buyers of the car than those who'll be writing about it from the launch event. But it is impressively stiff and focused. The days of comparing a cabriolet's chassis to a certain four-fingered chocolate bar wrapper are numbered. It takes some serious cornering speeds and vicious bumps to even make you think about it. But as we know, the axles and suspension of the M4 are specific M items, offering big increases in dynamic rigidity over the regular 435i cabriolet we tested back in April.

With the steering and damping up to sport mode it all gets very tight indeed, though the 'sport' steering just feels heavier. In the wet a theoretically softer chassis than the M4 coupe would be an advantage, but the honest truth is that it's so close in feel that you'd need an M3, an M4, and an M4 cab with back-to-back blind tests to even begin to accurately quantify any difference in driving feel. Impressive stuff.

Good car, but the noise disappoints

Weigh-in
The thing that doesn't need any scientific roadtesting to reveal is the weight. A 60kg saving over the old model might be good, but this is still a 1,865kg car with driver and equipped with the M DCT gearbox - the latter a 40kg addition. You can feel that 253kg weight penalty over the M4 coupe everywhere, though the impressive carbon ceramic brakes disguise it well enough. Certainly a big step up from previously weedy M3 stoppers, though we'll have to see how the standard steel ones cope when we get a chance to try them.

Technically, the same should be said of the motor too. The twin-turbo straight-six offers a powerful low and mid-range punch that the old S65 V8 can only dream of. And the headline power figure of 431hp is an 11 horsepower improvement too. That's before we even talk about 203g/km and claims of 30mpg plus too. But, out in the elements, the Convertible opens this new blown M motor to closer scrutiny of its character and ability to pluck the all important heart strings.

Lighter than the last car. Like a lot of things

The 8,000rpm-plus V8 was, of course, a master at that. This turbo six? Less so...

One fellow journo mentioned a slightly diesel-like undertone to the augmented intake noise. And with that seed of an idea planted the engine that springs to mind as an aural comparison is the 3.0-litre N57 diesel. Not exactly a halo Motorsport brand product.

Of course in terms of technology, dynamics and execution, the M4 Convertible is a massive success in every measurable way. The seven-speed M DCT gearbox will excite you at every click of the paddle. The customisable suspension, engine modes and corresponding displays (including the new HUD) will delight and fascinate you. But when you own a cabrio of this calibre, it should make a noise that entices roof-down motoring all year around. And, unfortunately, the new M4 really does sound better with the roof up.

BMW M4 CONVERTIBLE
Engine: 2,979cc 6-cyl, turbocharged
Transmission: 6-speed manual/7-speed dual-clutch auto (M DCT), rear-wheel drive
Power (hp): 431@5,500-7,300rpm
Torque (lb ft): 406@1,850-5,500rpm
0-62mph: 4.4 sec
Top speed: 155mph (limited)
Weight: 1,825kg (M DCT 1,865kg, both according to DIN/EU including driver)
MPG: 31 (M DCT 32.4mpg)
CO2: 213g/km (M DCT 203g/km)
Price: £60,730