Another prototype of the next-generation 2010 BMW 5 Series has been caught, this time while running laps around the Nurburging. The most noticeable change between this 5 Series tester and the last time one was caught is the mesh camouflage that covered up the grille has been removed, revealing BMW's signature kidney grille and some of the front fascia lines, which appear to be softer and more flowing than on the current car.

Dimensionally, expect the new 5 Series to add some space between the wheels by extending the wheelbase some four inches and widening the track. Overall length, height and width should also increase fractionally. Expect 17-inch wheels as standard equipment, with 18- and 19-inch wheels optional.As for powertrain speculation, it is believed the new 5 Series is expected to use variants of existing engines in BMW's line-up. The base engine should be a version of the automaker's 2.5-liter straight-six while top-range models will use the current 4.8-liter V-8, with the 4.4-liter twin turbo V-8 found in the X6 as another possible engine option. And of course, expect a re-worked version of the M5's 5.0-liter V10.

With the current E60 5 Series getting long in the tooth, the new one shouldn't be far away and may make its debut at either next year's Geneva or Frankfurt Motor Shows in time for the 2010 model year.