Road Test: Mercedes-Benz SLK SLK 55 2dr Tip Auto

You expect speed and handling to be central themes of any Mercedes wearing the AMG badge. But that's not the case with the SLK55 AMG. Of course it's plenty fast enough - a follicle-challenging 155mph is available - and naturally it handles sweetly thanks to a girder-rigid body structure and supple suspension. But the SLK55 AMG isn't really about either of these things. It's about efficiency instead.

It's fitted with a 422bhp normally aspirated V8 engine - a non-turbo version of the lump fitted in the CLS AMG - which uses 30 per cent less fuel than the model it replaces. It does this by shutting off four of the cylinders when you are just cruising, firing them back up again in 30 milliseconds when you stamp on the throttle. You don't notice the change.

The efficiency theme continues with the steering and handling. Speed sensitive steering assistance, dubbed AMG Direct Steer, makes the car easier to park and gets keeps things lively when attacking a series of bends. The best thing to say about it is that you don't notice it intruding unduly, so it clearly works fine, too.

As does the roof which whips up and down quickly and, yes, efficiently. However, the wind blast with the roof down is nothing short of a wind tunnel, so prepare to have your coif well and truly feured. Roof up, the SLK is as silent as a coupe.

So the SLK55 AMG does all the things you want from a convertible Mercedes: go fast, feel solid, stop quickly, steer accurately, and bring the outside in as required. But now it does so using less energy from the car and driver than ever before. The only feature that's not more efficient is the price tag. But then you expected that, didn't you?