Twenty Gallons of Gasoline
If you can go by vehicle, you must go by vehicle. The dead just cannot compete with the speed of a vehicle. Gas is important for things outside of powering tools and vehicles as well. A few Molotov cocktails can really slow down a zombie horde.
Outside of finding the gas, you will need something that can hold it. Most gas cans come in common sizes like one or two gallons. Your ability to get out of dodge, fast, will dictate your survival. You cannot pack up twenty 1-gallon gas cans fast.
The 5-gallon gas can is the better approach. Moving around just five of these makes much more sense. Its more efficient and you can fill them up silently no matter where you find gas. You will also want to keep a small bit of hose for siphoning.
The best approach is a gas tank on a trailer attached to the back of your vehicle. These come in varieties that can hold 50 gallons or more.