The news coincides with...

The news coincides with the release of official "teaser" pictures of the disguised five-door from Mercedes, seen here. The AMG version will rival Audi"s S3 - itself not due until 2005 - and is likely to get a high-powered version of the 2.0-litre four-cylinder petrol engine that will also be used in other A-Class models. However, sprightly performance and frugal economy will also be offered by a new 141bhp 2.0-litre diesel unit.

The sporty test car boasts the same 18-inch alloys as the new SLK, and has a squat stance thanks to lowered sports suspension. However, engineers will be working hard to ensure this car doesn"t suffer the same stability problems as early versions of its predecessor, which famously rolled in the elk test.

By far the most prominent features of both three and five-door variants are the reverse-angle C-pillars and big tail-light clusters, which will give the smallest Mercedes a distinctive appearance.

The firm"s own images - which look as if they"ve been taken by a spy photographer - have been released to mark the completion of the rigorous endurance testing and development schedule.

A spokesman told us: "We wanted to show how committed we are to making the A-Class totally durable. By releasing pictures of the disguised prototypes, people can see these are the cars we are using for testing and that we"re doing all we can to ensure that, whatever the weather, the A-Class will deliver."

Covering four continents and nearly 35,000 miles, testers have put two prototypes through their paces in extreme weather conditions and in a variety of driving environments, from the heat of Dubai to the icy roads of Finland.

Bosses say they have found few problems with the design. Yet despite providing these first images, Mercedes is keeping official spec details secret - expect more information closer to the A-Class"s Paris Motor Show launch in September. Both three and five-door variants will be on sale here early next year.