Doctor Drivel ) gurgled happily, sounding much like they
were saying :

They are diesel/electric.

Electric motors propel them.

Indeed. In exactly the same way as they do in diesel/electric trains.

Yep. Electric motors propel trains weighing 1000s of tons at over 100mph.

Indeed. Some get their electrickery from trackside cables.

Some get their electrickery from diesel engines powering generators, like
these trucks.

None are battery-powered.