The task of placing a value on a business is a highly complex procedure. Distribution firms may sell for 2-4 times earnings.
Retailers run the gambit.
Many rules of thumb then instruct you to add such things as inventory and real estate. Be careful in using any multiplier. You must know exactly what should be multiplied. You do not specify which aspect of the automotive industry you are interested in. Retail parts stores have uniquely different characteristics than do a new car dealerships, used car lots, service and repair facilities, quick lubes, auto rentals, etc.