Dodge SRT-10

With its 8.3-litre engine, the latest incarnation of America's ultimate muscle car has a 190mph top speed and will blast from 0-60mph quicker than any Ferrari currently on sale. But does the fact that it has a proper roof enhance the driving experience, or ruin it?

Badged Dodge SRT-10 in the UK, following a legal row which prohibits parent firm Chrysler officially naming it the Viper, the coupé is 30 per cent stiffer than the roadster. And, thanks to the addition of a rear spoiler, it has 30 per cent more downforce, too. Tipping the scales at only 18kg more than the roadster, it pumps out a stomach-wrenching 712Nm of torque from between 1,500 and 5,600rpm, meaning in-gear acceleration is simply incredible.

Adding a roof has benefited the car. It's certainly quieter - despite that monstrous Detroit truck powerplant throbbing away at your feet - and it's better to drive, too! The extra rigidity doesn't only help the handling, which isn't as wayward as you might expect, it also cuts some of the vibrations filtering through to the cabin, giving a less intimidating feel.

In corners the front stays pinned to the road, making the steering seem surprisingly quick and positive for a car that, under the skin, is about as svelte as a sumo wrestler. It all helps contribute to the settled feeling the model exudes, as the wide track and fat tyres ride over imperfections in the surface.

The engineers behind the SRT-10 Coupé have resisted the urge to add ESP or traction control, so if you lose the reins there is no electronic safety net to step in. It also means if you stamp on the accelerator while at a standstill, you will sit in a cloud of expensive tyre smoke. They have, however, fitted ABS, because this makes the car quicker round a track. The weak link in all this is the transmission. The gearlever, which features a knob designed for chunky hands, hints at the lack of finesse.

This is confirmed by first acquaintance with a clutch which suffers an absurdly long travel and very high biting point. The change itself has a frustrating element of vagueness that makes shifting up and down a rather tedious voyage of discovery. The interior is also a letdown. Some of the black plastic would look out of place even on a budget motor - which is as much of a shame as it is unanticipated on a car which is likely to cost in the region of ΂£80,000 and hopes to compete with the likes of Porsche and Ferrari.