THE AUDI R8 SPIDER has been a hot topic since way back in 2007. Now, finally, the days until its debut - likely at the upcoming Frankfurt Motor Show in September - are running down.

What will it look like? Something, you’d expect, like these photos of a mystery convertible version spied out testing around the Nurburgring in Germany (where else?). These may be the clearest shots yet of the upcoming soft-top monster.

According to US mag Car & Driver, Audi has opted to pass on the 4.2 litre V8 that powers the regular hardtop R8, skipping straight to the 5.2 litre V10 that powers the R8 V10.

The report suggests Audi may choose to add the V8 as an option at some point in the future, but that the V10 will initially be the only engine offered for the R8 Spider.

With weight-saving being a primary goal, Audi has opted to go with a soft-top rather than a folding hard top for its new convertible supercar.

Perhaps the most obvious design elements separating the Spider from its hardtop brother-in-arms are the absent ‘blades’ that run from the side skirts to the roof of the hardtop, and the addition of a longer, more prominent intake cut deep into the sides of the car.

The fuel cap has been relocated to the top of the rear guard, as opposed to the rear pillars (absent from the convertible R8).

While it’s likely to be somewhat distant from the production version, the R8 Spider shown in these photos features a roll-cage running through the inside of the car, up and along the line of the windscreen. (Audi will have other plans there.)

Car & Driver also reports that Audi has delayed the launch of the upcoming 2010 Audi A8 beyond its originally scheduled Frankfurt appearance, with the Detroit Motor Show now expected to host the big saloon’s debut.

GALLERY » 2010 Audi R8 Spider Spy Shots