BMW M4 Convertible

The question you want to ask is: why?

The cliché goes that if it’s not broken, then you don’t need to fix it. And to us: the last edition of the BMW M3 is far from a broken, tired product. I mean just look at it.

But, then, take a look at the new M4 convertible. Does the old M3 look tired in comparison? You decide.

Whatever you think aesthetically, under the skin of the Jekyll-and-Hyde M4 is the beating heart of a lion.

It’s a high-revving in-line six-cylinder Turbo. It displaces a tad under 3 litres, features two mono-scroll turbochargers, high-precision direct injection, fully variable valve timing and camshaft control.

If that sort of language gets you all lusty and you don’t know what it means – all you need to know is that it allows the BMW M4 Convertible to switch seamlessly from an undemanding everyday road car to one which feels totally at home on the race track.

And if you like your engines nice and twisty, then this might be the car for you. Huge reserves of torque, peaking at 550Nm, are available from just 1,850rpm – exactly the point at which maximum power of 431hp is attained. This is then maintained until 7,300rpm.

We haven’t driven one yet, but these digits should mean that there’ll be a never-ending surge from little more than engine tickover to the electronically restricted top speed of 155mph.

Pullaway is achieved in 4.6 seconds with the six-speed manual gearbox, or 4.4 seconds with the seven-speed M Double Clutch Transmission.

That’s way beyond Countach levels of sprint. This means, that in its everyman garb, serious cooling tech is needed to keep things in the black and out of the red.

An indirect intercooler maximises charge pressure and engine output, while the main radiator is supplemented by other coolers located in the sides of the engine bay for the high and low-temperature water circuits as well as for the engine and transmission oil (with the M DCT gearbox). An additional electric coolant pump helps to cool the turbocharger bearing mounts when the car comes to rest.

The lightweight magnesium sump has a special cover to minimise the movement of oil during high-G cornering, and an additional pump and sophisticated oil return system maintain stable oil circulation under hard acceleration and braking.

The quad exhaust system contains electronically controlled flaps which minimise back-pressure and ensure that the M4 Convertible has an unmistakable BMW M sound.

The optional seven-speed M Double Clutch Transmission effectively combines two gearboxes, each with its own clutch. This means that shifting is more or less seamless, which makes you quicker and uses less fuel. You can use either the gear shifter stick or the flappy paddles on the steering column, so both bases are covered. And yes, there’s launch control too.

Perhaps three is a crowd. And four is a party.