Highlights Open top grand tourer Turbocharged N55 straight-six Automatic gearbox Good recent service history Lovely condition Overview Among BMW's grand touring lineage, the F12 6 Series Convertible occupies a particularly compelling position.

Launched in 2011, it married elegant, sweeping bodywork with a beautifully appointed cabin, potent engines and a folding soft-top roof that could transform any journey into an occasion.

Composed and stable at motorway speeds, refined enough for continent-spanning trips, and blessed with the kind of kerb appeal that only seems to intensify with age, it remains one of the most complete open-air grand tourers of its era.

The interior, all leather and well-damped switchgear, has a quality of finish that holds up against rivals costing considerably more, and the boot is genuinely usable, even with the roof stowed.

While the 640d diesel found favour with many buyers for its impressive fuel economy and generous low-rev torque, the 640i tells a rathe...