I suspect the number of three or four-year-old Teslas on the market is more down to them coming out of lease or finance deals rather than concerns about reliability (although that might be a factor, too). It probably depends how long you wish to hold onto the car. If you're wanting a car to last a lifetime, we'd be a little concerned as we don't know how well Teslas will last and, at the very least, the batteries will require changing at some point down the line. Having said that, the batteries are unlikely to fail suddenly - they'll degrade over time - and if you're only planning on keeping it for a few years, it's unlikely to be an issue. I believe Allianz offers an aftermarket warranty for Teslas. Read more about warranties here: www.honestjohn.co.uk/cheap-car-warranties/