41 C.F.R. § 109-38.001
Experimental vehicles means vehicles acquired solely for testing and research purposes or otherwise designated for experimental purposes. Such vehicles are to be the object of testing and research as differentiated from those used as vehicular support to testing and research. Experimental vehicles are not to be used for passenger carrying services unless required as part of a testing/evaluation program, and they are not subject to statutory price limitations or authorization limitations.
Motor equipment means any item of equipment which is self-propelled or drawn by mechanical power, including motor vehicles, motorcycles and scooters, construction and maintenance equipment, materials handling equipment, and watercraft.
Motor vehicle means any equipment, self-propelled or drawn by mechanical power, designed to be operated principally on highways in the transportation of property or passengers.
Special purpose vehicles means vehicles which are used or designed for specialized functions. These vehicles include, but are not limited to: Trailers, semi-trailers, other types of trailing equipment; trucks with permanently mounted equipment (such as aerial ladders); construction and other types of equipment set forth in Federal Supply Classification Group (FSCG) 38; material handling equipment set forth in FSCG 39; and firefighting equipment set forth in FSCG 42. For reporting purposes within DOE, motorcycles, motor scooters and all-terrain vehicles will also be reported as special purpose vehicles.
41 C.F.R. §109-38.001