A good little summary of how to drive an EV as efficiently as possible:
http://www.energysavingtrust.org.uk/sit ... hicles.pdf
Of interest are:
Harsh acceleration has less effect on energy
consumption in a ULEV than in conventional vehicles,
however, there is still an energy penalty.
This is because the efficiency of an electric motor hardly drops at all even at full power. The battery efficiency (at least of current Li Ion designs) does drop somewhat at maximum output though so there is some loss of efficiency, but it is fairly modest. In contrast with an ICE engine (especially petrol) which is VERY inefficient when you floor it, partly due to having to run a rich mixture in the case of petrol.
High speeds increase energy consumption in EVs
more than they increase fuel consumption in
conventional vehicles. Typically in a conventional
vehicle, the most efficient speed (and therefore
maximum MPG) is achieved at approximately
40 – 50 mph, but the most efficient speed for
EVs is lower than this. The reason for the higher
energy consumption at speed is that air resistance
(drag) increases by the square of the vehicle speed.
With conventional vehicles this effect is somewhat
countered by the fact that vehicles are more
efficient in higher gears, but with EVs the countering
effect of gears does not come in to play. This is
why electric cars are well suited to city driving
where speeds are often lower.
As I've noted before, approximately 40mph in top gear is the most efficient speed for an ICE - faster than that and wind resistance starts adding a lot more drag, lower than that and you have to use lower gears that increase engine losses in proportion to road speed, however since an electric car only has one gear ratio the slower the better for efficiency.