DM, that theory only works for
me! 
I sincerely feel the longhood market has bottomed out and it's only going up from here.
As far as cars as investments, they can work but as a different kind of investment. You're doing good with a car if you can buy a good example, enjoy it for some years, and sell it for what you paid. Every car has running expenses, so there's no point counting that - the extra money is worth the additional fun you have, or you bought the wrong car.
Emanuel