**Diesel locomotives can't deliver enough power.** The power rating of the diesel generator on most locomotives ranges from 2 to 4 megawatts. The combined power rating of motors on high-speed trainsets range from 5 to 20 megawatts, depending on size and design speed.

Diesel engines are rated for maximum power, while motors are rated for continuous power. Motors can deliver much more than their continuous-rated power for a few seconds. This means much greater acceleration, and much greater power requirements, than any engine could provide.