Jack, Diesel is fine for trucks, busses, trains, etc.
By the end of WW2 the Germans knew that diesel subs were finished. They have to surface to run the diesels and were easy pickings for long range planes. They started producing a peroxide powered alternative to diesels.
This days with satellites the subs would be picked off by a long range missile as soon as they surfaced. Even at night or snorkel depth.
Perhaps the USA, Russia, China,UK,France are wrong about their nuclear subs? i don’t think so.
