BMW’s 1-series has been quite a hit, despite a less than rapturous response from some corners of the press when it was first revealed nearly six years ago.

Its combination of premium feel, rear-wheel-drive chassis and proven engines has made a real impact on the small family hatchback class, giving the Audi A3, VW Golf and upper rungs of the Ford Focus range something to think about.

As a result, the new, mk2 1-series is likely to keep changes minimal and go for evolution rather than revolution. While the current car’s looks initially attracted criticism, its flame-surfaced styling has proved to be a bit of a grower.

These spy shots of the new car show that the shape of the car has largely been left alone. Most noticeable changes will be tweaks to front and rear styling, some of which can be detected through this slightly mad disguise. Expect the front end to echo the softer, more conservative looks of the BMW 5-series GT and new Z4 roadster.

Engines are likely to be more about cleanliness than performance, at least initially. The combination of efficient dynamics and great diesel engines in the 116d and 123d has led to the current One being a bit of a green choice, and as with other BMWs, it leads the premium hatch class when it comes to high MPG and low CO2.

Chances are there’ll be M Sport variations, too, as well as replacements for the Coupe and Convertible further down the line. There’s also talk of a practical estate version, which may be closer in concept to the Mini Clubman than a mini-3-series Touring.

Expect an official unveil of the new BMW 1-series next year, with sales following in 2011.