Under the general definition of larceny, unauthorized use of a motor propelled conveyance is not truly an example of larceny. The reason for this is that the unauthorized use offense does not include any intent to deprive the owner of the vehicle while larceny must include such an intent.
A person who "borrows" a vehicle without the consent of the owner is liable to be charged with unauthorized use. However, that person could not be charged with larceny if he or she intended to bring the car back. This is the major difference. In larceny, there must be an intent to permanently deprive the owner of the vehicle. Unauthorized use occurs whenever the person uses the vehicle without the express or implicit consent of the owner, regardless of whether they intend to take the vehicle permanently.