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).

This is why overall energy consumption for new electric trains isn't
substantially higher than for older electric trains, despite their much
higher peak power ratings.

You seem to be talking about historic improvements which have reached a
plateau.

And a plateau is exactly what car engines have *not* yet reached, and
what the question was effectively about.
--
Roland Perry