The real important part:
By way of background, I would like to discuss how military vehicles manufactured in the United States are treated under the National Traffic and Motor Vehicle Safety Act, the authority for the Federal motor vehicle safety standards (FMVSS). The first qu estion to be answered is whether any particular vehicle is a "motor vehicle" as defined by the Safety Act, that is to say, whether it is a vehicle that has been manufactured primarily for use on the public roads. If we conclude that a vehicle is manufac tured primarily for on road use, it is a "motor vehicle," notwithstanding the fact that it may be sold "on the basis they would only be used for off road purposes." We see no way in which a seller can bind a purchaser to such use, and, certainly, such a restriction would not be binding on subsequent owners of the vehicle. As for individual vehicle types, to state the obvious, a tracked motor vehicle such as a tank intended for cross-country off-road terrains is not a "motor vehicle." If a vehicle, suc h as a military bus, has been manufactured primarily for on- road use, it is a "motor vehicle." However, NHTSA excuses vehicles from compliance with the FMVSS if they have been manufactured in accordance with contractual specifications of the armed forc es of the United States (49 CFR 571.7(a)). Furthermore, because the Safety Act does not regulate sales of vehicles to owners subsequent to the original one, the U.S. armed forces may sell military vehicles to the public at the end of their useful milita ry life without having to bring them into conformity with the FMVSS (however, because of safety policy considerations they have not done so with respect to M-151 jeeps and HMMV vehicles).