The key difference is the addition of the intelligent xDrive four-wheel drive system. It uses an electronically controlled multi-plate clutch to distribute power between the front and rear axles.
In normal conditions, 60 per cent of the engine’s output is sent to the rear, helping to retain the typical rear-drive BMW feel. If the system detects oversteer or understeer, however, it quickly shuffles torque between the axles to stabilise the car. The additional traction also means the xDrive M135i is 0.2sec quicker from 0-62mph than its rear-drive equivalent.
We found the M135i xDrive to be eminently capable on a snow-covered slalom, while stop-start manoeuvres on icy inclines were fuss-free and ice-covered corners could be dispatched in a surefooted fashion.
Even moderately deep snow was tackled with relative ease, as long as some momentum was maintained. Some of those capabilities were no doubt down to the test car’s winter tyres, but nevertheless, there’s no doubting that an xDrive-equipped BMW would prove both easier and more reassuring to drive in poor conditions.
More importantly, the addition of four-wheel drive doesn’t appear to have notably compromised the M135i. The steering remains precise and uncorrupted, while the xDrive means you can exploit the available power more controllably, which some might prefer. Multi-stage stability control also allows for a modicum of tail-out action, ticking the requisite box for many an enthusiast.
Should I buy one?
If you frequently travel to European ski resorts, and want a practical hatch with some punch, then this could be just the ticket. That's assuming, however, that you don't mind the fact it's left-hand drive.
Those who find the idea of an xDrive-equipped 1-series appealing can at least partially sate their appetite with the UK market 120d xDrive, which is available now for £26,190.
It may not have the M135i’s pace, but it’s still a thoroughly decent car to drive, albeit one that majors on practicality and efficiency.
BMW 1 Series M135i xDrive
Price £35,550 (est); 0-62mph 4.7sec; Top speed 155mph; Economy 36.0mpg (combined); CO2 182g/km; Kerb weight 1595kg; Engine Straight six, 2979cc, turbocharged, petrol; Power 315bhp at 5800rpm; Torque 332lb ft at 1250-5000rpm; Gearbox 8-spd automatic