BMW's 140mpg green machine

A shelved BMW concept capable of 140mpg has been put on display at the BMW Museum in Munich. Called the Simple concept, the boxy two-seater was created in 2008 but didn't see the light of a motor show because BMW bosses felt its tandem layout made it unsellable.

But the incredibly economical and unusual car, which has three wheels and tilts from side-to-side like a motorcycle, points towards the type of innovation we'll see on the 'Project i' cars BMW is currently developing. Project i is the umbrella name for a series of very small and very economical premium city cars, the first of which is due to hit the roads by 2015.

Sebastian Schelper, leader of the Simple project, was keen to point out that the car 'has no design' when we spoke to him at the BMW Museum during its unveil, but has its boxy bodywork purely to make it as aerodynamic as possible. It's powered by a 48bhp petrol engine, but at 450kg is so light that it can accelerate to 62mph in 'under ten seconds' and return an amazing 140mpg.

The car's name is an acronym of 'Sustainable and Innovative Mobility Product for Low Energy consumption', and although it won't make production, BMW has provided lots of detail about its dynamics. It features a hydraulic tilting mechanism that requires no effort from the driver, but its passenger cell makes it both stable at higher speeds and safe in the event of a crash.

Mark Nichol