If we were serious about reducing the environmental impact of cars, we'd change the one thing that damages the environment the most-- the process of manufacturing stuff to replace perfectly adequate older stuff that has simply gone out of fashion.
The average buyer keeps a new car for 71.4 months (according to AutoTrader), or just under the 6 years the loan takes to pay off. Then Mr. New Buyer trades it in, and starts the cycle over again. Lather, rinse, repeat from the time a buyer can afford his first new car (30?) until he dies.
I've got no data to back this up (sorry Mike), but I'd bet good money that the driving my stinky old hopped up VW until I die has significantly less environmental impact than buying a new EV every 6 years. I don't care if the EV plant has a sod roof and an army of contented robots welding on the spotless epoxied floor-- the steel, aluminum, plastic, motors, and batteries to build the green machine all came from all over the globe and didn't just teleport themselves to the shiny factory. Those same raw materials and sub-assemblies likely came from places where the environmental impact of mining and manufacturing was not a prime consideration. Building stuff new stuff is not environmentally friendly, no matter how pretty it looks on the showroom floor, or how good it makes us feel.