BMW plans to use four-cylinder engines for cars with power outputs of no more than 245bhp, and the German carmaker is said to be planning to introduce turbocharging to its four-pot powerplants. Cars with power outputs of more than 245bhp will use BMW's new straight six-cylinder engines.

BMW's four-cylinder engines will be built around the same new 2.0-litre aluminium block, with different power outputs delivered by using two different types of turbocharger and different engine management maps. The new block gets a new type of cylinder lining, which sees iron sprayed on at a thickness of just 0.3mm, instead of using conventional 1.5mm thick cast iron liners.

The most powerful of the four-cylinder engines will be introduced in the X1 SUV soon, and featuresa double-sided 'twin scroll' turbocharger, double Vanos variable valve timing and high pressure fuel injection of up to 200 bar. Lower powered four-cylinder engines are expected to feature just a single turbo, and the new engines are expected to make their debut in the all-new 3-Series, which is due in 2012.