http://www.treehugger.com/files/2009...-efficient.php



Less is More With Electric Motors Too
Electric motors are very efficient compared to gasoline or diesel engines, but it seems like there is still room for improvement. One promising company working on this is a spin-off from Oxford university called Yasa Motors ("Yasa" stands for "Yokeless And Segmented Armature"). Their electric motor was first developed for the Morgan LIFEcar high-performance hydrogen car, but its characteristics - 50% of the volume giving 2x the torque for the same power output - mean it could be used in other things than electric cars, including renewable energy generation and aerospace (lighter airplanes use less fuel...). Even electric bikes could benefit!

Scaling Up
Yasa motors has just got £1.45 million ($2.42 million) from a funding round with private investor Seven Spires Investments Limited, and a grant from the UK's Technology Strategy Board. This will help them develop a mass-produced version of their lightweight-but-powerful electric motor that can have applications in many fields, including electric cars and renewable energy generation.

In a 2007 white paper (pdf), they claimed a 95% peak efficiency, but back then they were only at a 20% improvement in torque, so it's probable that peak efficiency has been improved since then.
I haven't verified this but apparently, according to one of the comments in the page, this motor is the same type used for old 5.25" floppy disk drives.