Facelifted BMW 1 Series - exclusive studio pictures

The facelifted 2015 BMW M135i has been revealed, a couple of weeks after BMW issued full details on the revised 1 Series. The six-cylinder hot hatchback will go on sale in the UK this spring, and has made its public debut at the Geneva motor show.

The M135i gets the same powertrain as the M235i, with a 3.0-litre six-cylinder engine producing 322bhp and 332lb ft. That's enough to take it from 0-62mph in 5.1sec, or 4.9sec if you choose the optional eight-speed automatic transmission. The power output is still shy of rivals from Mercedes (A45 AMG) and Audi (RS3), however.

Read what we make of the second generation facelifted BMW 1 Series

The regular 1 Series gets revised front and rear styling, upgrades to its infotainment system and options list and, most important, a new range of three-cylinder diesel engines and revised four-cylinder units that promise more power but greater efficiency.

The diesels are all from the same family of engines that has just appeared in the latest Mini. However, since they're being fitted to the rear-wheel-drive 1 Series, they've been turned 90deg into a longitudinal layout. The entry-level model will be the 116d, which gets a 1.5-litre  three-cylinder unit producing 114bhp and emitting as little as 94g/km of CO2 with the standard six-speed manual gearbox, depending on tyre size.

A new version of ZF's eight-speed automatic transmission will be offered across the range, and its revised hardware and software helps to improve efficiency further; the 116d auto emits 96g/km of CO2. There will also be a manual gearbox-only 116d Efficient Dynamics, which uses a switchable coolant pump and combustion chamber pressure control to lower its CO2 emissions to as little as 89g/km.

There are also three 2.0-litre diesels, badged 118d (148bhp and 104g/km to 99g/km), 120d (188bhp and 114g/km to 109g/km) and 125d (221bhp and 121g/km). The first two of this trio will be offered with xDrive four-wheel drive, too, although the 118d xDrive will be restricted to a manual gearbox and the 120d xDrive is available only with the eight-speed auto.

As with the diesels, the UK won't be getting the most basic petrol engine, badged 116i; it's a 1.5-litre three-cylinder unit producing 107bhp. However, while the other engines are revised versions of the existing turbocharged 2.0-litre unit, they all bring more power and better efficiency. The 118i will be the entry-level edition in the UK, with 134bhp and CO2 emissions of between 134g/km and 125g/km, depending on your choice of gearbox and wheel size.

The 120i is the mainstream choice, with 174bhp, 184lb ft of torque and a 0-62mph time of 7.4sec (or 7.2sec with the eight-speed auto). Its CO2 emissions range from 136g/km to 133g/km. There's also the 125i, with 215bhp and 228lb ft of torque; it cracks 0-62mph in 6.4sec and returns CO2 emissions of 154g/km, or 148g/km with the auto 'box.