[Jeph]

If I were to wager a guess, I'd say the cord plugs into the left side of the detector because in MOST (not all, including Vipers & Hummers) cars, the lighter/socket is closer to the driver than the passenger.

Even the Boxster's lighter/socket on the right side, but I never had a problem with it. Nor have I had a problem in an TL, R32, 330i, Range Rover, Sentra, Civic, or any other car I've mounted it in (but I still need to confirm that with the Internets).