BMW M3 Convertible review (2008 onwards)

What – BMW M3 Convertible M DCT
Where – Munich, Germany
Price – £57,350
Available – Now
Key rivals – Mercedes CLK63 AMG Cabriolet, Jaguar XK Convertible, Audi RS4 Cabriolet

Summary - Mean and roofless M3 completes the hot 3 Series line up and debuts the new M Double Clutch Transmission

We like - Truly epic engine, fantastic new automated gearbox, relatively good value, hearing the V8 on full song
We don't like - Fuel consumption, weight blunts performance, not as focused as coupé

First impressions

The M3 coupé stunned, the saloon impressed - so what's left for the cabrio? Well, if nothing else chopping the roof off lets you hear more of the fabulous engine note. Which has to be a good thing. And we've got the first sight of the M division's new automated gearbox.Called M Double Clutch Transmission (M DCT), this seven-speed unit ramps up BMW's already impressive head start in automated manual gearboxes. Indeed, with a cheeky jibe at Ferrari it even claims to have been first with the technology, SMG apparently beating the supercar builder's F1 gearbox by six months.

Read more BMW car reviews

For the first time on an M3 Convertible there's a folding metal hardtop too. This is another USP for BMW, with key rivals still using traditional soft tops. With the roof up the styling loses some of the purity and aggression of the coupé, but few will mind the compromise.Roof down and the M3 offers al fresco fun for four, with a focus and intensity few can hope to rival. Only the RS4 Convertible can beat it on paper, the M3 simply demolishing cars like the CLK500 Cabriolet and Jaguar XK Convertible while simultaneously undercutting both by several thousand pounds.

Performance

In the new M DCT gearbox the M3's engine has found its perfect partner. This is proper track-inspired technology, brilliantly adapted to create one of the most exciting road cars this side of 100-grand. Only the forthcoming Nissan GT-R compares but won't be offered as a convertible.The Drivelogic software offers five different shift speed settings and a launch control mode, punching home ratios with real ferocity in the fastest, blurring to a more relaxed mode for when you just want to cruise. There's also a full auto setting, again with variable shift patterns, that works far more convincingly than previous SMG units.

It shaves a couple of tenths off the 0-62mph time, dropping it to 5.1 seconds. Acceleration is relentless, the shift lights above the rev counter counting up to the redline. Slam home the next ratio as the lights flash red and you're dropped right back into the powerband.The cabrio's extra 230kg undeniably blunts the M3's edge though. And with the real drama only coming in the last few thousand rpm, unleashing its true performance isn't always practical. The twin turbo 335i Convertible, meanwhile, has the same 295lb/ft of torque from just 1,300rpm and is less than a second slower to 62mph.

Ride and handling

That weight penalty makes itself felt on the road too. And here rivals like the XKR and CLK claw back some ground lost in pure firepower, the Jag in particular weighing in at a relatively svelte 1,635kg. Roof down there is no escaping the M3 suffers body flex on bumpy roads too.So is it just for poseurs? Well, purists will always prefer the coupé and the saloon is relatively discreet. So yes, by that measure the cabrio M3 is the biggest attention seeker in the range. But BMW wouldn't allow it to wear an M badge if it couldn't deliver as well.

Our test car wore 19-inch wheels and was fitted with Electronic Damper Control, both popular choices from the options list even with the respective £1,265 and £1,295 cost. Spring and damper settings have been changed for the cabrio too, with extra bracing on the rear axle and a thicker rear anti-roll bar. In Comfort mode, the softest of the three EDC settings, the M3 Convertible is acceptably smooth, although the big wheels don't do the ride any favours over broken surfaces. EDC Normal and Sport progressively ramp things up, the latter sending shudders through the car's structure and proving pretty pointless for the road.

Interior

Of all the premium manufacturers only BMW has successfully managed to tackle the button frenzy blighting many modern cars. And say what you like about iDrive, it successfully cleans up the dash and centre console. The system in the 3 Series is a lot simpler than that in the 7, and sat-nav is standard.Beyond embossed M logos on the headrests and blue and pink stitching on the excessively thick wheel rim there's little else to distinguish the cabin though. Special SunReflective leather, developed by BMW's motorbike division, keeps the seats up to 20 degrees cooler though, just one of many pleasing details.

Economy and safety

Well, the M DCT gearbox at least improves things a little. But there's no escaping this is a seriously thirsty car, the combined average of 23mpg improving on the manual by 1.1mpg. CO2 is also down from 309g/km to 293g/km, but this is purely academic as far as the tax man is concerned. Safety-wise there's a full armoury of electronic safety nets, including the show off's M Dynamic Mode on the Dynamic Stability Control system. And if you defeat that and the car thinks it's going to tip over pop up roll bars emerge from the rear bodywork, while seatbelts pre-tension and airbags deploy.

The MSN Cars verdict: 4/5

That BMW has managed to retain such a large degree of the M3's magic in the Convertible version is very impressive with the added enjoyment of a glorious soundtrack from that incredible engine with the roof down. Then there's the new M DCT gearbox, representing a big step on from the previous SMG unit.The extra weight, softer chassis and body flex do diminish the M3's hardcore appeal though. And in that respect it's hard to ignore the fact the cheaper 335i's smooth, more flexible power delivery and only marginal performance handicap probably suit the convertible's character better than the M3's manic, race derived V8.

Ratings out of five: BMW M3 Convertible
Performance ****
Ride & handling ****
Interior *****
Safety ****
Price ****
Practicality ***
Fuel economy *
MSN Cars verdict ****

Need to know
Petrol engine 4.0-litre V8
Power (bhp) 414
Torque (lb/ft) 295
0-62 (secs) 5.1
Top speed (mph) 155
Combined mpg 23
CO2/tax 293/35

Get an insurance quote for an M3
More BMW M3 images from Live Search

Also consider

BMW 335i
Audi RS4
Mercedes CLK 500
Jaguar XK