[kgermino]

> On a personal note, me and most of the people I know think more in terms of miles than years.

I think that partly depends on how you drive and where you live. I'm in a snowy climate: my engine might have no problem going 250,000 miles, but there's virtually no chance the body is drivable after 30-40 years of rust.

With that, I tend to buy a car in years, for example: "I'm hoping to have this for the next 6 years".