The next-generation BMW 1-series has broken cover undergoing testing in Germany, although you’ll need to look carefully to recognise the changes.The prototype is disguised under a chopped-up five-door body from the current model, but reveals that BMW will provide the next 1-series with an extended wheelbase to improve interior space.This 1-series test car has a modified B-pillar and doors, which have been extended front and rear with larger openings to rectify one of the 1-series’ biggest weaknesses - the awkward entry to the rear. BMW has also extended the car’s tracks to improve stability and handling.BMW insiders have said that the suspension (MacPherson struts up front and multi-links at the rear) has also been revised, gaining slightly modified geometry and a greater number of aluminium components to sharpen responses and reduce weight.The steering on the new BMW 1-series will adopt an electro-mechanical rack, as seen on the Z4. “With the growing concern over fuel economy and CO2 emissions, it brings a number of advantages while using less energy,” said a source involved in the development of the new model.BMW is planning a highly modular approach to the second-generation 1-series platform and suspension. The components have been designed to underpin a wide range of models, ranging from the X1 off-roader through to the next 3-series and an as-yet-unconfirmed MPV. Munich insiders said that the wheelbase and track widths on all models will vary quite dramatically.Alongside standard rear-wheel drive, BMW is planning a four-wheel-drive version of the chassis, with its new torque-vectoring system. Engine choices will include modified versions of the Mini’s 1.4 and 1.6-litre four-cylinder, which have been conceived, developed and produced in partnership with Peugeot. They will join a new line-up of BMW engineered turbocharged four and six-cylinder petrol and diesel engines.