Worst of the worst? Late 80's Ford truck, with the dual fuel tanks. When I worked at a power plant for a year (after getting out of the navy), they had it as a shop truck, for getting parts, etc. They had bought it from the company that had done the construction on that plant, so it was already a half-beaten work truck when purchased.
Whenever you'd try to switch from one tank over to the other one, seems like at least half the time the valve would get stuck between tanks, and you'd get nothing.....and the truck would stall out. You'd have to pull over, get under the truck, and bang on that transfer valve a bit to see if it would un-stick. We got used to just switching over at 1/8-1/4 tank, so at least if you couldn't get it to switch over, you could always switch it back (which it did flawlessly), and still have fuel to get back.
The only redeeming factor to that truck? I didn't own it!! 🙄