Shopping Cart + Gas tank. Makes siphoning fuel from those abandonned vehicles a breeze. When you’re ready stick a trunk on, or a battery and a welding rig.
Alternatives, Shopping cart + FOODCO buddy. Seriously, that thing is so damn useful and fairly easy to craft too-- the only problem is getting your hands on a water purifier or a hand press/die kit. A single storage battery will provide you enough quickly purified water and dehydrated meat to last you forever and a day.
Other Alternatives: Raid an RV. RVs are secret treasure troves. Forget the gas tanks, steal the water tanks. They’re bigger. Plus they’ll usually have some clean water.
Take the Kitchen unit while you’re at it. Boiling water eats up a lot of time, but if you can’t make fire or a hotplate it’s pretty good. Actually if you can find semi-filled water, even only 7% full or something that tank should be enough to last you for quite a while unless you’re doing a lot of cooking or crafting that requires water.
Ah, those 30 Gallon drums. Nothing like quaffing water direct from the source. Taps are so out this season.
Other Other alternatives. Military APCs. External Gas/Diesel tanks are huge. 55 Gallon drums. One day I shall forge myself a shack out in the woods, a moonshine still, wooden barrels and begin brewing while I fish the local river or swamp.
Once you have a car, scrap them all and fit them in.