While the new BMW 135i coupe might well be the automatic choice among enthusiasts, it’s the calmer but impressively frugal four-cylinder diesel powered 120d and 123d coupe models that will drive the majority of sales. BMW took the wraps off the 123d this week alongside the 135i. Although its more toned town looks were overshadowed by those of its petrol sibling, the 123d is probably the better guide for what the majority of 1-series coupes sold in the UK will look like. Have a closer look in our gallery.The entry-level 120d coupe serves up an impressive 177bhp and 258lb ft for a 0-62mph time of 7.6sec and a top speed of 141mph, while averaging 58.9mpg and emitting just 128g/km of CO2.With sequential turbocharging and a host of other changes to the induction system, the 123d adds a further 27bhp and 37lb ft, taking the car’s power and torque to a class leading 201bhp and 295lb ft. The latter figure is as much torque as the 135i is blessed with.BMW claims 0-62mph acceleration in 7.0secs, a top speed of 148mph for the twin turbo diesel, as well as 54.3mpg and an exceptional 138g/km. All of which makes us wonder if the 135i coupe’s keenest competitor may end up being its own, twin turbocharged twin.