BMW's M4 Convertible combines virtual supercar pace with a sleeker look and feel. What's not to like? Jonathan Crouch reports.
Ten Second Review
The BMW M4 Convertible delivers. With at least 431bhp from an inline turbo six, you now get much better economy and emissions, a more talented chassis, less weight, more performance and better value. Plus there's a 'Competition Pack' option that adds extra attitude and boosts power to 450bhp. Overall then, it sems that plenty of progress has been made here.
If you and the BMW M4 Convertible are going to get along, you first need to make a pact. This involves ditching any lingering resentment over what has happened to the M badge. You might remember it with faintly rose-tinted spectacles as something that once adorned refugees from the race track and lightweight homologation specials rather than overweight SUVs and crossovers. In truth, BMW was fairly liberal with the badge even back then, attaching it to a convertible version of the hallowed E30 3 Series. Accept that it doesn't mean 'Motorsport' any longer and instead just denotes the fastest models in BMW's line-up and you should find no point of principle coming between you and the latest M4 Convertible. Only the most determined BMW devotee is going to come across as in some way affronted by a car this potent, which packs 431bhp in its standard guise or as much as 450bhp in more focused 'Competition Pack' form. It's a model that has shed 60kg compared to its 3 Series predecessor. This is progress and progress is looking extremely good.
Before car manufacturers got a bit better at it, lopping the roof off a coupe would turn the resultant convertible into a bit of a wobbler. It's basic physics. Take the lid off a shoe box, for example, and it flexes and warps. Latterly, car makers understand chassis rigidity a whole lot more and now know where to put high-tensile materials and where they can get away with lightweight parts. As a result, this M4 Convertible is 60kg lighter than its 3 Series predecessor and thanks to parts like the carbon fibre engine strut brace, offers decent body rigidity. Power comes courtesy of a twin turbo 3.0-litre straight-six which does its best work from just 1,800rpm, offering it a huge advantage in real world driveability. Peak power is rated at 431bhp in the standard model, with a massive 550Nm of torque available, an increase of some 40 per cent over its predecessor. The sprint to 62mph takes just 4.2 seconds with the dual-clutch gearbox, beating the six-speed manual to the benchmark by 0.2 seconds. There's also an Active M Differential to help improve traction and an M Dynamic Mode in the stability control software, which allows owners a degree of slip angle without turning the safety net off completely. The steering is an electromechanical set-up featuring three modes: Comfort, Sport and Sport+. We'd want to look at the optional 'Competition Package' which, as well as the 19bhp power hike to 450bhp, also includes Adaptive M Suspension extensively tuned to the enhanced performance and handling. With this option, you additionally get revised springs, dampers and anti-roll bars, along with reconfigured driving modes.
Design and Build
The 4 Series Convertible is a good-looking car but in M4 guise is an even more purposeful affair. Signature M design features include a power dome in the bonnet, a sculpted front apron with triple air intake and a black double-slat kidney grille. There are 19-inch M double-spoke light alloy wheels, flared front and rear wheel arches, M side gills and Air Breathers behind the front wheels, plus polished slanting quad exhaust tailpipes. With the 'Competition Pack', you get exclusive forged, machine-polished, weight and rigidity-optimised 20-inch M alloy wheels with exclusive multi-spoke M styling and mixed tyres (265/30 R20's at the front and 285/30 R20's at the rear). The three-part metal roof provides significantly improved noise insulation compaed to the old 3 Series Convertible set-up and folds down in just 20 seconds. BMW have also cribbed Mercedes' Air Scarf front seat-mounted neck warmer, in this case calling it 'Air Collar'. There are a number of practical features like the boot loading aid which raises the folded roof cassette when it's stowed in the boot to give owners access to their belongings in just 6 seconds. The luggage capacity has also increased to 370-litres when the roof is closed and 220-litres when it's stowed. The cabin gets electrically-adjustable and heated leather M seats, an M steering wheel, chrome trim and three-colour M stitching. With the 'Competition Package' you get special lightweight M sports seats and seatbelts with woven-in BMW M stripes.
Market and Model
Here's the part where we proceed to tell you that this BMW represents a bargain at just over £61,000. But really, it does. When the original E30 M3 Convertible went on sale in 1988, it wasn't a cheap car. Adjusted for inflation today, that model would cost over £70,000. That bought you 215bhp worth of power, got you 30 miles per gallon on a good day and not too much in the way of interior refinements. It was also the heaviest rear-wheel drive 3 Series you could buy, something that many choose to overlook. Now you get almost double the power and superior fuel economy to boot. Even Mercedes wants around £70,000 for potent versions of its C-Class Cabriolet. Drive the two of them back to back and we'd be mightily surprised if you decided the Merc was the better steer. Equipment-wise, apart from the exterior styling treatment, the folding roof and the lovely seats, you also get front and rear park distance control, exterior-folding mirrors, Shadowline exterior trim and a full BMW Professional Media package with upgraded Bluetooth system. A bit of fun is the free BMW M Laptimer app, which allows owners to analyse their personal driving style. Once their smartphone is hooked up to the car - via USB cable or the car's snap-in adapter - drivers can operate the BMW M Laptimer app using the iDrive Touch Controller. The app then records speed, longitudinal and lateral acceleration, engine revs, the gear engaged, steering angle, accelerator position and fuel consumption. The data can subsequently be analysed via graphic displays on a smartphone, including driver reaction times.
Cost of Ownership
It's hard to know quite what to pitch the M3 Convertible up against when it comes to cost of ownership figures. Its nearest spiritual rival would be the Mercedes-AMG C63 Cabriolet in 476bhp form, but this doesn't get particularly close. Where the Mercedes returns as much as 218g/km of CO2, when we look at an M4 Convertible with an equivalent gearbox, the number comes back at a more tax friendly 203g/km. The BMW's 32.5mpg combined cycle fuel figure isn't bad for the performance on offer too. As lovely as the Mercedes is to own, those efficiency figures look likely to swing residual values firmly in the BMW's favour. If the C63 is throughly trampled, how about something even more focused than the BMW? A Porsche 911 drop top maybe? Aside from the fact that you'd be having to shell out over £82,000, bear in mind that the Porsche is a). slower, b). has a boot less than a third of the size, c). charges you more for rear parking sensors and such like and..... well need we continue? The BMW has it covered. The only possible issue may be the BMW's softer residual values as a result of its own popularity.
Part of the appeal of buying the last M3 Convertible was that dropping the roof got you closer to the astonishing soundtrack generated by its feral V8 engine. The inline turbo six of this M4 Convertible might not cede anything in outright go, but it's a more muted-sounding car and that's a bit of a shame. Still, it's one of the few downsides to the development of this particular model. It's now a good deal better-looking, to our eyes at least, is way more efficient and it's refreshing to see BMW offer keen drivers the choice of a semi-auto or a manual gear shift. The Munich maker has created a very special vehicle in the M4. It has needed to. The old M3 coupes and cabriolets used to occupy their own niche before being rudely gatecrashed by resurgent Mercedes AMG and Audi RS models. Even Porsche's Boxster and Cayenne muscled in on the act. These days the M4 Convertible looks set to re-establish its superiority. Normal service has been resumed.