i'm not sure about speed, but i think the range is only like 5 km?...they talked about during the solar panel talk...if you only drive 3.5 kms to work, you can theoretically drive on electric power, then let the roof recharge the battery while you are there, then drive home on charge the sun gave you for free...as i said though, theoretically..clouds, type of driving conditions, etc all come into play.