BMW M6 convertible (2012-2017)

The BMW M6 convertible is based on the standard 6 Series convertible, but adds a powerful 560bhp 4.4-litre turbocharged engine, as well as a host of electronic systems to improve the handling. A coupe version is also available, which gets a carbon-fibre roof instead of a retractable fabric hood. The styling has been given an aggressive makeover to make it stand out from other models in the range – and so it should with a price tag of nearly £100,000.

In isolation, the M6 convertible is very fast, but you'll have more fun in an Audi R8 Spyder convertible or a Porsche 911 cabriolet - neither of which will cost much more to buy.

Thanks to stop-start, direct fuel injection, variable valve timing and the turbochargers, the M6 uses around 30 per cent less fuel than its predecessor, despite a 52bhp advantage. Drive enthusiastically, though, and the fuel consumption can drop as low as single figures - the car costs £490 a year to tax too. Repair bills and servicing won’t be cheap either. You can expect to lose around 50 per cent of its value over three years, too, thanks to the supercar-style pricing.

Under the bonnet is the same engine as the BMW M5 saloon. The 4.4-litre twin-turbo V8 produces 560bhp and launches the convertible from 0-62mph in 4.0 seconds. A seven-speed gearbox delivers extremely fast gear changes, but isn’t as smooth as the eight-speed automatic fitted to standard versions of the 6 Series. The M6 sends its power to the rear wheels, but there's still loads of grip in the corners and, thanks to stiffer suspension, it won’t roll around even at high speeds. There's a huge array of settings for the gearbox, suspension, steering, throttle response and traction control, so you can tailor the car's behaviour to your driving style – but it feels too big and heavy to be a proper sports car.

You can choose to boost power and grip further by specifying the M6 Competition Package, which increases engine power by around 40bhp. It also features a M Differential on the rear axle which increases grip when cornering. Buyers can raise the top speed to 186mph by choosing another option, the M Driver's Package.

Sports seats designed specifically for the M6 are heavily sculpted to hold passengers in place, but soft Merino leather included as standard means they remain comfortable, even on long trips. The suspension can be set to three different modes – the softest of which is supple and deals well with poor road surfaces. Even in the firmest mode it’s always bearable. Leave the roof up and the interior is almost as quiet as the coupe – even at motorway speeds, a conversation with passengers in the back is easily possible. The M6 is a car that's been designed to be useable every day, with an explosive burst of acceleration when the opportunity presents itself. There’s enough room in the back for adults, too.

With the roof up there's 350 litres of boot space – lower it (a process that takes around 19 seconds) and that falls to 300 litres. The rear seats can accommodate two full-size adults at a squeeze, or can double up as extra luggage space and there's a sizeable glove box for your valuables in the front. Thanks to a larger 80-litre fuel tank than its V10-powered predecessor, and fuel consumption improved by 30 per cent, the M6 Convertible can travel a useful 480 miles between fill-ups. However, the long bonnet makes it tricky to pull out at tight junctions and its large size also makes parking difficult.

The build quality in the M6 is superb, especially inside, which features expensive leather and carbon fibre trim. But this is a car that's been designed for those who’ll want to exploit the performance on offer. It's likely to be used as a track car at some point in its life, so parts such as brake pads and tyres will have to deal with more wear and tear than most ordinary cars. Given proper maintenance, though, it should be just as reliable as less-powerful BMWs and the option of carbon-ceramic brake discs that never need replacing should solve this problem.

Priced at just under £100,000, the M6 convertible costs around £5,000 more than the coupe but approximately £4,500 less than its closest natural rival, the Jaguar XKR-S convertible. Considering the 407bhp 650i Convertible M Sport costs less than £80,000, the M6 is an awful lot of money for not much more, but the performance is truly astonishing. Standard equipment includes dual-zone climate control, a heads-up display and sat-nav with a 10.2-inch colour screen. BMW also made its 'remote services' standard in 2018, letting you check on the car and even lock its doors or flash the headlights using a smartphone app. Carbon ceramic brakes and 20-inch alloy wheels (instead of the standard 19-inch wheels) can be ordered as options.