The BMW 6 SERIES GRAN COUPE (2015-18) 640D 4DR GRAN COUPE 3.0 DPF SS 313 EU6 M SPORT LIMITED EDITION AUTO8 is a four-door premium coupé-style saloon, pairing executive-car comfort with sleek looks and useful rear doors. It occupies the UK’s luxury class, alongside the Audi A7 and Mercedes-Benz CLS. Mycarcheck data comes from 13 lookups covering eight distinct vehicles, so it offers a useful snapshot rather than a broad reliability verdict. The checked cars averaged 28,000 miles and just over one previous keeper; average annual use was 4,000 miles. The average private-sale valuation was £29,700. The 640d suits drivers wanting motorway comfort, strong pace and distinctive, low-slung presence, rather than a compact city runabout. Four doors make it practical for passengers and family use, while M Sport trim adds a sportier character. This used BMW 6 Series Gran Coupe blends grand-tourer comfort with executive polish for reassuring long-distance journeys.