As used in this chapter, unless the context otherwise requires: 1. "Chase vehicle" means a motor vehicle that accompanies an experimental vehicle while operating on a highway. 2. "Experimental vehicle" means a vehicle with an unladen weight of six thousand pounds [2721.55 kilograms] or less which may be equipped with any configuration of axles and wheels and which is primarily powered by some source other than a combustion engine, muscle, or an animal.