"dennis@home" wrote in message
eb.com...

it doesn't matter how powerful the engine is as long as its more than the
average for the journey. The power to accelerate doesn't come from the
engine, it comes from the battery.
You can accelerate as fast as the battery and electric motors allow. As
long as you don't do it too often and flatten the battery, then you would
find it hard going.

If the battery is depleted somewhat after acceleration the engine provides
power to the electric drive motors and to top up the batteries very
efficiently as the engine will be running at its most efficient while doing
so, unlike a directly mechanically coupled engine to wheels setup via an
inefficient and power sapping transmission. Constantly varying the speed of
an engine from near zero revs to near maximum is highly inefficient.

A largish car doing 70mph only uses about 20-30% of the power of the engine.
Most of the time a car's engines is way oversized and carrying all that
surplus weight. The surplus power is for acceleration. Electric drive and
kinetic brake recovery using supercapacitors and a decent battery set can
mean engines are much smaller. Having range extenders means the engine can
be built light, small and optimised to run at its sweet revving spot.