Roadster a worthy rival to Audi’s TT.

Both look “interesting” and neither has a head-on rival. The model seen by BMW as the biggest challenger is the Mazda MX-5, which is sold with a traditional soft top and with a folding hard top. This is a classic rear-wheel-drive chassis and has been the world’s best-selling open car for many years.

I do not think an MX-5 enthusiast is likely to be lured by the Mini Roadster, which lacks the Mazda’s elegant body.

Maybe the Audi TT Roadster is at risk from the Mini. It is more expensive and its entry range has front-wheel drive, like the Mini. Why not save a few thousand quid and buy the Mini Roadster?

Roadster prices open at £18,020 for the Cooper-engined model, then rise to £20,905 for the Cooper S, then £21,630 for the diesel-fuelled Cooper SD and leap to £24,860 for the John Cooper Works flyer – the most expensive Mini model, pending the arrival of a JCW Countryman. All but the JCW are available with six-speed automatic gears.

The Roadster shares Mini DNA in the oversized speedometer (not to everyone’s taste)

and in the fiddly toggle switches which hark back to the simpler layout on the BMC Mini of 1959. In concept it is a drophead variant of

the Coupé.

On test were manual versions of the Cooper S and Cooper SD. At seven seconds for the 62mph sprint, the petrol S is 1.1 seconds quicker than the diesel SD. However, the figures mislead because the SD will not reach 62mph in second gear, so its 8.1 seconds from 0-62mph includes a change into third gear. Once there, it will hold its own with the Cooper S.

In real driving, its much greater torque (the highest of any Mini) makes it a swifter car, both smoother and quieter, and without the annoying pop-pop-pop of the exhaust when you lift the throttle on the Cooper S in town.

The SD also has lower CO2 (118g/km) for cheaper tax and better economy (by more than 9mpg on official tests). Back-to-back tests over the same route showed 37mpg for the Cooper S and 49mpg for the Cooper SD.