I don't think cars equate well to collectibles like stamps, since they require so much continued maintenance especially in the later years. You are going to drive that thing, aren't you? Then maybe your kid decides to take it out one day and...
A la "Ferris Beuhler's Day Off". FYI, there are plenty of 50+ year old cars in collections that are not driven. One could easily argue that using a car for its intended use (driving) is exactly the same as using stamps for their intended use - slapping a mint #65 on an envelope to make up postage on, say, one's electric bill payment. Many car collectors see their cars as we see our stamps - something to be preserved. Still, I can only imagine the rush of getting behind the wheel of a '72 Charger with a 426 Hemi and slapping the pedal to the metal. I have a 2006 Charger with a 5.7L Hemi which I use as my daily runner, and that's as close as I will ever get. Still lotsa fun.
As a bit of an aside: At what point does using low-denomination stamps affect the rate paid? How many 3-centers on an envelope pop the envelope up to the next weight class? At what point is one REQUIRED to use a larger envelope (thus, slightly heavier) in order to fit all of the low-denom stamps that one is trying to use up???