I am not as optimistic as you that 4x improvements are possible, but I certainly hope you're right! We'll also need major improvements in electricity generatio

I am not as optimistic as you that 4x improvements are possible, but I certainly hope you're right! We'll also need major improvements in electricity generation and distribution. To charge a battery of ~300 kWh in roughly an hour, even over an industrial supply like three-phase 480V AC, would require in excess of 600 amps! That's more than three times the maximum current a large, modern house can draw at 240V, and requires conductors over 1000 kcmil, or more than 1" diameter copper. On an ordinary 15A, 120 VAC circuit, it would take an entire week to charge the car. That might make fuel cells attractive. Never underestimate the bandwidth of a station wagon full of tapes, and never underestimate the energy transmission potential of a supertanker or freight train full of oil or hydrogen.