See the bolded? Being able to drive around is useful. Particularly if you are trying to get away from a zombie horde bearing down on you.
open scene: our tattered gang sees hundreds of zombies coming toward them from down the road. The group, struck with looks of horror and fear turn to Rick, their leader, for guidance.
Rick: "The zombie horde is almost here. Everyone into this van. We're going to put 25 miles or so between us an these zombies and then we'll regroup."
Copeman: "Rick, we can't do this. This van has been sitting here for three months. The gas in the tank is pretty much useless."
Rick turns the key and the van's engine roars to life.
Rick: "Looks like it's working to me. Everyone in, the zombies are on our ###."
Copeman: "Rick. The gas has been sitting idle in the tank for three months. It's probably starting to change characteristics. It will cause damage to the engine."
Rick: "What the hell are you talking about?!? The car is running!"
Copeman: "Well, sure, it's running now. But eventually the van's engine will be damaged and the van may seize up."
Rick: "It seems to be running just fine!"
Copeman: "Yeah, but in a week or two the van may seize up. And that's because the gas is pretty much useless."
Rick: "A week or two?!? These zombies are going to eat us in about 10 seconds. Everyone get your asses in the van."
Everyone but Copeman jumps in the van
Copeman: "I'm telling you that gas is pretty much useless. We should look for a fresher source . . . "
The zombies converge on Copeman taking him to the ground as the van speeds off into the distance, leaving the zombie horde far behind.
Lori: "The gas sure seems useful to me."
fade out. end scene.