BMW has released details of its second-generation 1-series, which features a larger body and a new engine line-up.

The new 1-series is still rear-wheel drive, and BMW is quick to suggest that its "high precision steering" has "no interference from the drivetrain". Two petrol engines and three diesels are available at launch, with power outputs ranging from 116ps to 184ps (see below). All are four-cylinder TwinPower Turbo units.

The new petrol engines, which are making their debut in the F25 1-series, feature Valvetronic variable valve lift and Double-VANOS valve timing control, twin-scroll turbos and high-precision injection. BMW says the new petrol engines offer power increases over the previous engines, but also up to 10 per cent better fuel consumption.

The diesel engines use aluminium cylinder blocks, variable-geometry turbos and have reduced internal friction compared to the previous generation of 2.0-litre turbo engines.

A 116d EfficientDynamics edition is due shortly. This is likely to employ similar fuel-saving strategies to the 320d EfficientDynamics, with longer gearing and a focus on low-speed refinement. The 116d EfficientDynamics is expected to emit 99g/km of CO2 on the European driving cycle, giving it tax advantages in some markets.

A new eight-speed automatic transmission is available as an option. BMW says this transmission is only fractionally heavier than the existing six-speed automatic. The 1-series returns better fuel consumption and CO2 emissions figures with the new automatic than its does with a manual gearbox - though whether that advantage is also true in real-world driving conditions remains to be seen.

The new 1-series is 85mm longer than the outgoing car, with a 30mm longer wheelbase. Though the overall width has increased by only 17mm, the front track is 51mm wider and the rear track has grown by 72mm. The result is a small increase in legroom and greater luggage capacity.

BMW 1-series engines