BMW's twin-turbo M5 | Auto Express News | News | Auto Express IT’S M for Monstrous! With a 507bhp 5.0-litre V10, the BMW M5 hardly lacks punch – but Auto Express has learned that the wick is really being turned up on the next-generation model. Following in the wheeltracks of the Audi RS6, the next M5 is rumoured to boast a new twin-turbocharged V10 engine. The new unit is expected to be a development of the firm’s 564bhp 4.4-litre twin-turbo V8 which will power the upcoming X5 M and X6 M models. It will produce in excess of 600bhp and is likely to be paired to an F1-style KERS system, allowing the driver to boost performance at the touch of a button. However, the new M5 is expected to keep an eye on fuel economy too with a new system that shuts down cylinders when they are not needed. We’ll learn more about the new M5 and the 5-Series next year.