"Roland Perry" wrote in message

In message
,
at 03:53:07 on Wed, 12 Aug 2009, John B remarked:
You might be able to apply some of the engine-improvement
technology to DMUs, but can electric motors be made any more
efficient?

Yes:
1) three-phase induction motors instead of synchronous DC motors
2) regenerative braking

These have been done.

So you can't make them *more* efficient, then (starting today,
obviously).

Note the comments I made upthread about the new Desiro City train, of
which the manufacturer says, "The lightweight design of the train and
the bogies combined with an intelligent vehicle control system reduce
overall energy consumption by up to 50 per cent compared to preceding
models." I assume the comparison is with other electric Desiros, such
as the 350s, so it looks like significant further savings are still
available.

However, I think that electric trains are already so efficient that the
amount of improvement available can't be as much as cars, which start
from a much worse position. After all, you can't do as much to improve
the aerodynamics of a train as you can a car, and there isn't an idling
engine you could switch off at stations.