It's hard to answer conclusively but early evidence is good. Their vague goal is a million miles on the drivetrain of the 3 but they warranty 100k miles, so the million is really an aspiration. There are people with 300k on their Ss already. No spark plugs, no oil to change. No fan belt, no transmission, no spark plugs or gas filter or muffler. Tires are the main thing people change. The early worries were about battery degredation. No degredation for me after almost 40k miles.