BMW HAS JUST launched the M6 coupé, and quite a machine it is, too. But impressive as its 500bhp V10 is, it does make you wonder just how much power is really necessary. Particularly as the M6 weighs in at a hefty £80,755.If ballistic performance isn’t the be-all and end-all, and 80 grand is a bit steep, then this new 650i is worth looking at – especially as it will beavailable now in coupé and convertible guises, unlike the currently fixed-roof-only M version.The Six was introduced in 2003 with a 4.4-litre V8, but this engine has just been replaced with a new 4799cc powerplant. It produces 367bhp, up from 333bhp, and is both cleaner and less thirsty than the motor it supersedes.The 650i coupé hits 62mph in 5.4sec, with the convertible 0.3sec behind, half a second quicker than the 645. A six-speed manual gearbox is standard and there is the option of both six-cog Steptronic automatic and SMG automated manual transmissions.We drove an auto convertible, which is ideal for those wanting relaxed cruising with added sun. However, despite the increased capacity, there’s precious little difference between the old and new engines.As well as launching this new V8, BMW has introduced a Sports version of the 6-series. It gets bespoke 19-inch alloys, an M-Sport steering wheel, sports seats, anthracite headlining and birchwood interior trim.The standard 650i coupé costs £52,115 (Sport £53,965) and the convertible £57,515 (£59,365). We reckon they’re worth the near six grand over the six-cylinder 630i.