M-badge marks the spot

The 1-Series M-coupe is the smallest car to carry BMW's high-performance M badge and the only one that won't use M as the designation. Photo / Supplied

BMW deliberately badged its latest go-fast model the 1-Series M-coupe to avoid confusion with the mid-engined M1 supercar of the late 1970s.

The smallest car to carry the high-performance M badge is the only one that won't use M as the designation, unlike the M3, M5 and M6.

There is another concession to the prestigious M ranking, too. The twin-turbocharged engine under the bonnet of the 1-Series M-coupe isn't exclusive - it's already used in the Z4 sDrive35is roadster, the first time a standard production powerplant has appeared in the M line-up.

The M-coupe replaces the 135i as the flagship of the 1-Series range and is likely to appear in New Zealand in July or August. No word on price yet, but it can be expected to be considerably more expensive than the 135i's price tag of $89,500.

Both cars share a boosted 3-litre straight-six engine. The unit in the 135i delivers 225kW/400Nm. The M-Coupe's powerplant puts out 250kW at 5900rpm and 450Nm from 1500-4500rpm - and a further 50Nm under an overboost function.

The M-coupe is about half a second quicker to 100km/h than the 135i and only fractionally slower than the V8-powered M3 over the same sprint. The M3 weighs 1605kg, the 135i 1525kg and the M-coupe 1495kg.

Power goes to the M-coupe's rear wheels via a six-speed manual gearbox and the rear axle includes a differential lock for optimising traction.

BMW hasn't said whether the dual-clutch automatic available on the 135i will become an option for the M- Coupe.

An M-Dynamic Mode also offers a more flexible engine set-up, which can switch between relaxed and torque-oriented or tuned for maximum power at the touch of a button.

There's been a host of EfficientDynamics tweaks, too, resulting in fuel economy of 9.6 litres/100km (29.4mpg) and CO2 exhaust emissions of 224gr/km. EfficientDynamics is BMW mild-hybrid protocol, using energy-saving devices such as regenerative braking.

BMW's M engineers have also set out to make the M-coupe faster around corners as well as quicker in a straight line.

The M-coupe is 55mm wider than the 135i to house wider front and rear tracks and bigger, 19-inch alloy wheels.

Up front, the M-coupe retains much of the 135i styling but the rear end gains a more aggressive-looking lower bumper and the quad tail-pipes that are a signature of the company's M models.

An M button on the steering wheel introduces a more aggressive throttle mapping, while an M Dynamic switch changes the threshold of the electronic stability control. It can be switched off for track days.

The leather steering wheel, with traditional red and blue M stitching, is one of the interior parts to feature an M badge.