Parkers overall rating: 3.5 out of 5 3.5

The 3.2-litre straight-six engine delivers 343bhp without the aid of a turbo or supercharger yet the performance on tap matches the significantly more expensive Mercedes SLK55 AMG. Performance is identical for both Roadster and Coupe and 0 to 62mph comes up in just 5.0 seconds while the top speed is limited to 155mph. From start-up, the rev-counter advises a limit of 5000rpm, but as the engine oil warms, the guideline lights on the rev-counter progressively permit up to 8000rpm.

It comfortably pulls from below 30mph in sixth gear (accompanied by a deep burble from the exhaust), but flooring the accelerator in lower gears sees the revs rise quickly and a flood of power unleashed, with a rising mechanical scream. Of course this performance isn't without its costs - the claimed fuel economy is just 23mpg but in everyday driving that's difficult to achieve, with 19mpg being more realistic.

The Z4M is happiest on smooth, open roads as the incredibly stiff suspension struggles over anything but a perfect surface and quickly becomes crashy over uneven or bumpy roads. This makes it an uncomfortable car to drive and far from relaxing on cross country routes - even cat's eyes produce jolts into the cabin. A heavy clutch and gear change make it almost impossible to drive smoothly in town and the overly sensitive throttle mean it is all too easy to end up kangaroo-ing away from the lights - selecting Sport mode exacerbates this problem even more.

It is better on the motorway but the wide tyres do have a tendency to tramline and the car feels constantly busy so it's not a comfortable long distance cruiser. The firm set-up does there's minimal body roll in corners though plus there is plenty of grip - even in the wet. However the steering disappointingly lacks feel and the Z4M doesn't corner particularly neatly or smoothly.