It's correct though.

ICE efficiency in a car ~ 20% for a car, gas to wheels.

Worst case scenario :

• diesel running to generate electricity (the engine stays at its efficient point): 45-50%
• battery efficiency to charge 85%
• battery to movement efficiency ~85%

Electric cycle efficiency : ~33%

You need to add ~15% overweight for EV, making a conservative 28% total cycle efficiency.

It is definitely the energy density which makes the difference.