Although BMW has already confirmed the existence of not only the new 8 Series, but also the M8 coupe, it's still fun to see ongoing development continue. Today, our spy photographers have caught the also upcoming M8 convertible testing at the Nurburgring. It's actually been a few months since testing at the Green Hell has taken place because during winter months the famed track is nearly unusable. It's even more dangerous covered in snow and ice.

But it appears springtime has come to Germany so that means automakers are heading back for serious track testing. Notice that the M8 convertible test mule shown here has fairly light camouflage, with its sleek headlights and wider kidney grille in relatively clear view. Compared to the standard 8 Series, the M8 will be a bit wider, thanks in part to the fenders and side sills, for a more aggressive (and appropriate) appearance. Powering this open top beast is the 4.4-liter twin-turbo V8 tuned to deliver around 600-630 hp. Other M8 additions will include bigger brakes and wheels and quad exhaust pipes, among other things.

Remember, BMW also showed the M8 Gran Coupe Concept earlier this month at Geneva, which will go head-to-head against the Porsche Panamera Turbo S E-Hybrid as well as the also just revealed Mercedes-AMG GT GT63 S 4-Door. Expect for BMW to reveal the 8 Series as well as the M8 coupe and convertible sometime by the end of this year.