Don't they have "New Car Smell" in a a spray thing? I think maybe you are buying the wrong cars if you get bored with them so quickly.
I have purchased two new vehicles. My integra and my wife's montero sport, 1998 and 2000 respectively.
The Mitsubishi was last years model, purchased on New Year's Eve, so we got a pretty good price on it. Wife still has hers, minivan killed mine last May. Only thing worn out on hers is the paint. You get so much more for your money when you buy used, especially when it is a hairdresser's car like a miata
It does have a leather interior, and smells like a new pair of gloves with the top up.