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BMW M4 Convertible review

The Good

  • Exceptional performance
  • Surprisingly economical
  • Looks the business

The Bad

  • Significantly heavier than the Coupe
  • Engine sounds a bit artificial
4

Blasting through the countryside with 431hp at your disposal and the wind in your hair is the perfect mid-life crisis remedy. Or is it? Ben Griffin got behind the wheel of a BMW M4, with the roof down in the rain, to find out.

Virtually everything about the new BMW M4 is better on paper than its predecessor, but there are fans who still pine for the E92’s V8. Some have complained the new TwinPower Turbo six-cylinder lacks the same soul, the same panache.

Admittedly the V8 sounds far, far better, but the M4 Coupe is a riotously fun car and it should be even more so with the roof down. The question is whether losing the roof softens the experience, or emphasises it?

M for menacing?

Design

The BMW M4 Convertible looks like the M4 Coupe, thanks to the folding hard-top roof. As a result, it’s a fairly aggressive-looking car from most angles, with gaping air intakes in the front bumper providing particular menace. It’s even more striking from the rear thanks to the flared arches and wide back bumper. Overall, it’s far removed from the classy, upstanding standard 4 Series, as it should be.

The folding hard top roof improves the aesthetic compared with a fabric alternative, provides a quieter cabin than it would otherwise, and will probably have fewer cats clawing at its surface. 

BMW has managed to shed 60kg of weight compared with the M3 Convertible, thanks to the use of carbon-fibre reinforced plastic (CFRP for short). Even so, the M4 Convertible is considerably heavier than the M4 Coupe: 1,750kg versus 1,500kg – about the weight of three average British men. 

That’s a significant increase considering some cars, BMW’s own Z4 included, put on comparatively little weight in the transition from coupe to convertible.  

The well-insulated roof opens and closes in 20 seconds at up to speeds of up to 8mph, which is fast enough when the heavens open, but feels like an age if someone is driving behind you.

Compared with the Porsche Boxster, Jaguar F-Type Convertible and Audi RS5 convertible, which all open in around 30 seconds, 8mph seems a bit of a disappointment. You may as well pull over and stop or go for tactical roof operation at the traffic lights.

Practicality

The BMW M4 Convertible is, like the M4 Coupe, more practical than some of its competitors because it has two rear seats. Rear legroom isn’t particularly generous, but it’s not a major problem travelling in them, unless you’re unusually tall.  

The car lacks rear doors so there are no storage bins in this area, however BMW does provide a small compartment between the seats. The front, meanwhile, has good-sized door bins, a large enough glove box and two cup holders so you can handle a drive-thru takeaway with ease.

Our test car was fitted with split-folding rear seats (£170) for a little extra practicality in carrying long loads, the extended storage option (£155) which gives you a few extra cubby holes and an armrest with a storage area (£140). 

Boot space drops from 445 litres in the M4 Coupe to 370 litres in the Convertible. Put the roof down and you end up with 220 litres, which is going to make big shopping trips a struggle – especially if you like to pose in the supermarket car park with the top dropped as you load your groceries.

If you do have the roof down and find yourself struggling to load the boot, the new Loading Aid lets you raise the roof slightly at the push of a button, creating a bigger loading area and giving you more convenient access. 

Performance & handling

The new-generation M4 Coupe and Convertible ditch the 5.0-litre V8 seen in its predecessor in favour of a 3.0-litre straight-six with two turbochargers. In the Convertible it has more work to do in lugging around an extra 250kg, but straight line acceleration isn’t too far off the Coupe’s. 250kg is no match for 550Nm of torque and 431hp. 

0-62mph takes 4.6 seconds with the standard six-speed manual and 4.4 seconds with the M DCT seven-speed automatic. That’s only a few tenths of a second behind the lighter M4 Coupe, but about half a second quicker than the V8-equipped Audi RS 5.

The numbers don’t do the engine justice, mind you. Push the pedal and within a couple of seconds you’ll be doing illegal speeds, and it will continue accelerating towards scary numbers, leaving your wig on the asphalt behind you. 

With the roof up, the engine note is aggressive and suitably loud but not particularly nice. Strict fun police EU regulations and the push towards eco-friendliness mean BMW has to augment the sound of the six-cylinder lump using the car’s speakers, which makes it sound a bit artificial and forced. 

Luckily, with the roof down everything changes. The whoosh of the turbo, the roar of 431 horsepower and the satisfying pop of the exhaust when you lift off the accelerator – everything is a hundred times more dramatic and visceral as each sound smacks into your unguarded ears.

The steering is razor sharp, the grip remarkable and the ride composed enough to make you push your luck in the bends. You can, however, feel the extra weight when you slam on the anchors (even if you have the £6,250 Carbon Ceramic brakes like our test car) – though not so much it ruins the experience.

The M4 Convertible comes with various settings to adjust the driving experience. Adaptive Suspension as standard means you can make the ride less harsh on bumpy roads by selecting Comfort. You can also adjust the steering over three levels of increasing stiffness, tweak the ferocity of the gear changes and the responsiveness of the accelerator pedal. Usefully, you can store your preferred settings in the M1 or M2 buttons on the steering wheel.

The M4 Convertible is almost as adept at slow, mundane commutes as it is at high speed. The addition of Adaptive M suspension and the silky smooth automatic gearbox means slow traffic is no problem whatsoever. It changes gear quietly and efficiently, particularly in the Comfort driving mode, so you could use it as a daily driver, in theory, especially now the UK seems to enjoy longer bouts of sunshine.

Over really bumpy roads the M4 Convertible can feel slightly harsh, but you would expect that in a sports car. If comfort was a major concern, you would buy the standard 4 Series Convertible anyway.

We had no issues driving with the roof up or down. With it down, there’s little or no wind buffering at motorway speeds, while the heated steering wheel (part of the £695 Convertible Comfort package) and heated seats (standard) did their bit to keep us toasty.

Economy & environment

Losing the V8 really has an impact on the running costs of the BMW M4 family. While the heavier convertible takes a slight hit because of the extra weight, 31mpg is better than the slower RS 5 Cabriolet’s 25.9mpg. A Mercedes E-Class E 350 BlueTec Cabriolet offers 51.4mpg, but takes more than two seconds longer to hit 62mph from standing.

The Mercedes SL-Class is a closer bet when it comes to performance, but loses the two rear seats and costs £10,000 more for the base 333hp SL 400 model, which offers 36.7mpg and 178g/km of CO2. 0-62mph takes 5.2 seconds so the M4 Convertible wins here.

Obviously the moment you drive the M4 Convertible hard fuel economy figure will drop through the floor, even with the addition of its stop-start system. At least the 213g/km of CO2 (203g/km with the M DCT) means £285 to tax a year.

Equipment & value

The M4 Convertible is the most expensive car in the M4 family, roughly £5,000 more than the M3 Saloon and M4 Coupe. It comes with a fairly generous spec, including an 8.8-inch colour display, DAB digital radio, the aforementioned heated front seats, cruise control with stop function, Merino leather upholstery, Active M Differential and 19-inch M double-spoke alloys. 

There are, however, a fair few worthwhile upgrades that took our test car to £72,190. The head-up display (£825) is great for navigation as it puts directions in your line of sight (or tells you how lairy you are being in Sport mode), while the seven-speed M DCT (£2,645) offers improved performance, fuel economy and emissions.

Arguably the extra weight needs the big Carbon stoppers, but more than £6,000 is a big ask. Still, that money could be the difference between you and a ditch.

Safety

As the BMW M4 Convertible is heavier and lacks a roof, it’s a little less safe. But those Carbon Ceramic brakes are still going to help you come to a halt in rapid time. The M4 is based on the 3 Series and that’s a five-star Euro NCAP rated car so expect it to be safe, with a number of airbags, long crumple zone and German engineering all doing their bit.

Verdict

The M4 Convertible is less capable and less nimble than its M4 Coupe sibling, but that’s the price of going topless. Such is the noise of the engine and pace on tap, we found ourselves forgetting about the extra weight and limited boot space.

A Porsche Boxster is cheaper and even more fun to drive but you lose the rear seats. It’s the same story for the Jaguar F-Type, although the V6 and V8 roars are momentus. The Audi is a brute and maintains the V8 vibe, but is less involving to drive, not to mention slower.

Really it all boils down to this: If you need the extra seats, the M4 Convertible is exciting and lairy enough to put a huge smile on your face. If you only need two, the F-Type and Boxster are slightly more sporty, though not by much. If you want a high-performance car that lets you bring three friends (and some of their luggage) along for the ride, there are few better options.

Specification

Engine3.0-litre TwinPower Turbo six-cylinder
Power425bhp (431hp)
Torque405lb/ft (550Nm)
Acceleration0 to 62mph in 4.6 seconds
Emissions213g of CO2
Economy31mpg
PriceFrom £60,745

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