By 2004, enabled by the availability of rare-earth magnets with high magnetic strength, Alstom had developed permanent-magnet synchronous motors (PMSM) which were suitable for rail vehicles. They were smaller and had a higher efficiency than asynchronous motors and a higher power-to-weight ratio, as well as having the potential for lower noise levels. The AGV was one of the early applications of the new motor design, using 720 kW prototype motors weighing 730 kg. By 2008 the motor's continuous power rating had been respecified to 760 kW.