Motor vehicle means any vehicle for which evidence of title is required as a condition precedent to registration under the laws of this state but does not include trailers.

Motor vehicle also means any engine, transmission, or rear axle, regardless of whether attached to a vehicle chassis, that is manufactured for installation in any motor-driven vehicle with a gross vehicle weight rating of more than sixteen thousand pounds for which motor-driven vehicle evidence of title is required as a condition precedent to registration under the laws of this state.