you may never have to buy another ev. It should be easier to up-grade than to buy a new car. With every new inprovement in batteries, and electric motors. Exchanging what you have could be cheaper than buying a new car. Also think of third market pug-ins. that you could customize your ev with. Get a lead-acid battery to run your lights, air , heat,and sound system on. Leave the expensive batteries for range.  The point I am trying to make is it will be easier and cheaper to do up-grades than to have to buy a new car every two years to get the newest tech. I'm sure your members can come up with a lot of ideas on what can be done to Ev's that the auto makers havent even thought of. This could be another reason why they are dragging their feet on EV's. Customers wont feel they have buy new cars every two or three years.