Regenerative braking does not capture 100% of the force used to accelerate to that speed. Far from it. According to this article: http://www.teslamotors.com/bl

Regenerative braking does not capture 100% of the force used to accelerate to that speed. Far from it. According to this article: http://www.teslamotors.com/blog/magic-tesla-roadster-regenerative-braking http://www.teslamotors.com/blog/magic-tesla-roadster-regener... The Roadster's regen braking is at most 64% efficient. I'm guessing in real driving scenarios, it will be much less.