EDIT: This numbers are wrong. Take a look at my next post down below! It is known fact that required power raises aproximately with CUBE of speed. Doubling the speed requires eight times the power. Tesla has 185kW electric motor that is capable of accelerating it to maximum speed of 135mph. It also has 50kWh of charge. I did some calculations based on these numbers and came up with this table: SpeedPowerTimeRange (mph)(kW)(h)miles 50.01532026599 100.16656650 150.31972955 302.024.6739 404.810.4416 456.97.30328 509.45.32266 5512.54.00220 6016.23.18185 6520.62.4157 7531.71.6118 9054.80.982 105870.5760 12013090.3846 1351850.2736 Range in this table means how far will you get driving at given constant speed and how long it will take. Regenerative braking is obviously not counted in. These numbers are not absolute but they do ilustrate the situation to some degree. Some observations: Driving it to the max will drain the batteries in less then half an hour, in that time you've driven about 40 miles Driving it mainly at low city speeds will give quite good range - way above advertised 250 miles Ataining good range at higher speeds is still quite far away. Baterries will have to increase their capacity several times. People will be inclined to drive more slowly - in this way their range will increase considerably EPA Highway standard demands about 48.3mph average speed and Tesla is quoted to have 250+ miles range acording to this standard. My calculations predict 266miles range at constant 50mph, so these numbers are not way off.