For comparison's sake, my former tin box econo-hatchback weighed 3 times as much. Thank heavens it was well designed enough not to fold in half when I was T-boned by an early '70s Caprice doing at least 35 mph.
... with buses and all delivery trucks banished to other roadways... No problem. Plus all of these would be two-seaters at most.
Yes, which goes back to my original point about my ol' 1800lb-ish Plymouth Champ. Pure physics will dominate the ideal weight of the car in relation to reasonable crash survival requirements under real world driving conditions where other people are likely to be driving heavier vehicles. This car, while admirable in what it demonstrates, is still apparently enslaved to the limitations of what energy it can harvest, thus its astounding weight... or lack thereof.