The argument for DRM in the car MIGHT fly in cars that are leased (which in my lay-person's brain sounds somewhat similar to a license for using software), but there can be absolutely no reason for preventing me from accessing information on something that I own outright.
Its not like I bought a license to drive the car (that was provided freely (sans a few yearly fees) by the government of my state), I own the metal. What possible argument can there be for preventing me from reading the information in my car's engine?
e-credibility: the non-guaranteeable likelihood that the electronic data you're seeing is genuine rather than somebody's made-up crap. - Karl Lehenbauer