The Mini One is available with either a petrol or a diesel engine. The petrol is a turbocharged 1.2-litre three-cylinder unit, producing 101bhp and 133lb ft of torque between 1400rpm and 4000rpm. It can reach 62mph from rest in 9.9sec, and a top speed of 121mph. Mini claims combined fuel economy of 61.4mpg and CO2 emissions of 108g/km. This figure could rise slightly, to 109g/km, if you choose anything larger than the standard 15in steel wheels.
The petrol engine is also available with a six-speed automatic transmission instead of its standard six-speed manual. Mini has yet to release performance details for the auto, but its fuel economy does take a minor hit; the combined average is 58.9mpg, with CO2 emissions of 112g/km.
The Mini One D gets a milder version of the three-cylinder turbodiesel in the Mini Cooper D. It produces 94bhp and 162lb ft of torque, enough for a 0-62mph time of 11.0sec and a top speed of 118mph. As you might expect, the diesel is considerably more frugal than the petrol, with combined fuel economy of 83mpg and CO2 emissions of as little as 89g/km (rising to 92g/km if you choose larger wheels).
Mini hasn't announced an on-sale date for the One, let alone prices or final specifications. However, we'd expect the petrol Mini One to start at around £14,000; that's a modest increase on the outgoing car's starting price of £13,500, but there should be improvements in refinement, real-world economy and standard equipment to compensate for that.