Spy Shots: BMW M5 prototype gets towed off the 'Ring

Occasionally, we find ourselves wondering why manufacturers continue to insist on testing their prototype vehicles at the infamous Nürburgring. Yes, the track is 13 miles of some of the most abusive variations in elevation and apex around, but it's also flooded with legions of hungry spy photographers just waiting to publicize the carmakers' latest efforts. You'd think they'd come up with a locale with a smidge more privacy.

But the truth is that the Nürburgring offers a unique combination of length, speed and legality that's difficult to come across elsewhere in the world. Those three factors combine to allow engineers to push vehicles well past what the common buyer will ever experience, and sometimes, that means pushing a vehicle all the way to mechanical failure. We aren't exactly sure what caused this particular BMW M5 mule to go lame, but we're guessing that the testing was well worth what was bound to be the mountain of paperwork facing these guys when they get back to the office.

At least the X5 seems to be up to the task of pulling its sportier brother around.

[Source: CarPix]