.. without increasing charging voltage or current or even changing the supercharger hardware. Its really simple. Just cut the energy consumption ( wh/mile ) of the car in half. If the Model S is rated at 320 wh/mile and charges at 300 mph from the supercharger, a car that consumes 160 wh/mile will charge at 600mph with the same charging power. A car that only consumes 160 wh/mile is impossible you say? In order to do the cars need to be smaller, more aerodynamic, and lighter. A 3000 pound car with a 0.19 coefficient of drag and small frontal area can achieve 164 wh/mile at constant 60mph. They've already been made, in the late 1990s. http://avt.inel.gov/pdf/fsev/eva/genmot.pdf The good news is that back then they needed a 1200 pound pack to have an 80 mile range and a modern Tesla pack that achieves 200 miles in such a car might be as small as 500 pounds with today's technology. The only caveat is that it is unknown if the 32kWh pack needed can charge at 96kW ( which would be 600mph ). The cells that can charge at that rate may be different from the ones used today by the Model S.