As mentioned elsewhere, the most common issue is using old Save files. Anytime you change mods, you are changing some of the files. If the Save folder contains a file of the same name as one in the new mod set-up, it is not overwritten. That might be part of the issue. I don't think the game simulates fuel tank damage, though it does seem like it sometimes... The big thing is to find the most efficient speed, especially after you are past bingo. If you have the patience, the batteries never truly run down all of the way, so you could submerge and do about a half of a knot at a time the rest of the way home. Come up for air, of course. Also, the fuel goes way beyond what they say it will... just keep driving until you can't.
