The biggest advantage is the shape which drastically reduces air resistance and 3 wheels which reduces rolling resistance. Everything else in an EV is almost as efficient as it can possibly be. Aptera is about 100Wh/mi while a tesla model 3 is 200-250.

Weight/rolling resistance would be second so battery gravimetric density and better tires is the next thing to improve. We can probably get small sedans slightly under 200Wh/mi or 5 miles for every kWh.