Spied! 450 Horses for M4
The new M4 Coupe and Cabrio models were confirmed to be powered by an in-line six-cylinder turbo engine. It is expected to have two or three turbos and develop around 450 hp. M-fans will be pleased to hear that though a V6 turbo engine was considered, BMW decided to stick with the traditional BMW layout of an in-line six cylinder engine.
Source: 5Series Spies