I like it. We might want to take some extra efforts to make sure the odometer is accurate, but there's pretty strong incentives to fool with odometers already.

Apparently the average person pays 150-400 in gas taxes per year now. I guess the depreciation from mileage on car is of a similar order of magnitude. And we seem to do OK now: https://en.wikipedia.org/wiki/Odometer_fraud

(I'm sure people cheat on gas taxes, too.)