[SideburnsOfDoom]

> Existing cars, if driven 20 times as much, would wear out 20 times more quickly

Citation needed. I don't think they would.

[frankus]

You're right, instead of "would" I should've said "might". I was taking the parent's assumption as a given for argument's sake.

[SideburnsOfDoom]

I think it's safe to assume that cars driven 20 times as much wear out somewhere faster then the normal rate, but less then 20 times as fast. Some of the wear is due to time, some due to thermal cycling (turning on and off, which happens a lot less for the high-use vehicle) and only some is linear with use.