Second try; for some reason the forum/internets ended up eating my previous post. @Mods: please do not delete the empty post, because it points to a problem with the forum software -- the forum should've rejected my empty post for not containing the minimum of required characters. I'll tell Tosa in a minute.

Petrol (internal combustion) engines are in fact terribly inefficient compared to electric engines -- both at delivering speed and at delivering torque. Diesels are significantly better than petrol engines, but still not nearly as good as electric engines. The one thing petrol and diesel engines have going for them is that you can store a lot of energy in a relatively small form-factor: say a car-tank. This is much more difficult with batteries or capacitators (much the same): it is not possible to store those amounts of energy in this fashion in a similar volume.

Incidentally diesel power locomotives are usually a hybrid: diesel powered generators to run the electric engines which run the train.