Owner Jeff Chabotte bought the car in thoroughly neglected condition and spent weeks with his father and son bringing the futuristic Bimmer back to life. The slew of scoops and nacelles behind the seats might not be aesthetically beautiful, but they're authentic to the appearance in the film. For authenticity, Chabotte even keeps the busted taillight from Griff hitting it in the movie.
As Rutkowski finds during his drive, Griff's BMW poses absolutely no threat of chasing down the DeLorean to 88 miles per hour. There's actually a pretty good reason for that, though. The interesting story involves how the producers procured this gray-market 633 CSI to be in Back to the Future II.