With the question 'how good is the BMW 6 Series' is linked the question 'just how versatile is the modern car platform?'.

Because, beneath the unconventionally-styled skin of BMW's big coupe and cabriolet (and four-door Gran Coupe), lies the same architecture you'll find beneath all of BMW's large rear-wheel-drive cars, including the latest 5 Series, the 5 Series GT, 7 Series saloon and even the £200k Rolls-Royce Ghost.

Can you really take a platform used for a full-size limo and adapt it to make a convincing open-top GT? We'll see.

What's already clear is that, as is now the norm in the BMW range these days, the badging gives no clue to the engines under the 6-series' long, sculpted bonnet. The 640i features a 316bhp 3.0-litre, six-cylinder turbo, while the 650i gets a 402bhp 4.4-litre twin-turbo V8. There’s also a 309bhp twin-turbo 3.0-litre diesel, badged 640d.

The same engines feature in all variants of the 6-series, including the Mercedes-Benz CLS-rivalling 6 Series Gran Coupe.

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