The diesel 640d is the cheapest version to run by a country mile. Stick to SE spec with 18in wheels and it’ll emit a respectable 149g/km of CO2 and the official combined fuel economy figure is 50.4mpg. Although it’s unlikely that you’ll get quite that much to the gallon in the real world, our experience suggests that an MPG figure in the mid to high-30s isn’t too hard to achieve.
The 640i’s cheaper purchase price might tempt you, but it emits 179g/km of CO2 on 18in wheels and can only manage an official fuel economy figure of 36.7mpg. As for the V8 models, they all emit more than 200g/km and are likely to have real-world fuel economy that starts with a two.
The range kicks off with SE, which has 18in wheels, two-zone climate control, cruise control, leather seats, heated front seats, front and rear parking sensors and a 10.2in infotainment system with sat-nav and DAB radio.
Next up is Sport, which is available on only the 650i. This adds 19in wheels, comfort front seats with lumbar support, nicer leather and dark chrome highlights. At the top of the regular range is M Sport (available on all but the M6), which gets sportier styling inside and out but no extra kit.
If you go the whole hog and order an M6, you also get adaptive LED headlights, four exhaust pipes, bigger brakes, an upgraded stereo and sporty ‘M’ touches inside and out.
All 6 Series Convertibles have traction control, stability control and the usual selection of airbags. Automatic emergency braking is available as an option, along with lane departure warning. Euro NCAP hasn’t tested the 6 Series, but the 5 Series it shares a platform with scored five stars. As for security, Thatcham Research gave it five stars for resisting theft and four for resisting being broken into.
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