These are believed to be the first spy pictures of the BMW hydrogen hybrid technology undergoing testing.
The tech, revealed yesterday by autocar.co.uk, could be used by the next-generation Mini and the front-wheel-drive BMWs planned for 2014.
The system combines a conventional front-drive powertrain along with a hydrogen fuel cell, electricity-storing supercapacitors and an electrically driven rear axle.
As can be seen in these pictures, BMW engineers have already built functioning prototypes based on 1-series hatchbacks converted to front-wheel drive.
Company engineers say the “fuel cell hybrid technology” is designed to allow a vehicle to travel emissions-free in city centres, a feat beyond the ability of regular petrol-electric hybrids.
This drivetrain will fit into today’s Mini Clubman, making it likely that it could become an option for the front-wheel-drive BMW and Mini models that are at least four metres long.