A car is really a capital investment. The moment you drove it off the lot, it depreciated in value even with zero miles. If you really wanted to be a stickler for accounting standards, the expense you would record is the depreciation. Then, every year, you could look up the value of the car in Kellys Blue Book and record accordingly. This does seem a bit complicated however :-)
Incidentally, I too buy cars for cash and hold on to them for about 15 years typically. I think this is the best way to buy cars.