Imagine, if you will, the apocalypse. A mushroom gets a little out of hand, and suddenly everyone is zombies. Twenty years later, no one’s manning the gas pumps or working the refineries, but suddenly you’re tasked with driving some magic child across the country. How are you going to do that?

This, of course, is the question that lies before Pedro Pascal’s Joel in HBO’s The Last Of Us, as well as Troy Baker’s Joel in Naughty Dog’s The Last Of Us on which it’s based. But the show, out of the two, gives us an explanation for how a cross-country road trip is supposed to go when the world’s gas has broken down into non-flammable waste. The problem is, its explanation makes no sense.

In the early minutes of The Last Of Us’s fourth episode, we see Joel siphoning fuel out of a moss-covered car. He tells Ellie that all gasoline has decayed to nearly water, and they’ll have to stop every hour to siphon “fresh” gas from parked cars. Some quick Googling tells us that the pair’s gets, depending on drivetrain options, a maximum of — if they’re averaging 60 miles an hour through the vast expanses of middle America, stopping every hour means stopping every 2.4 gallons of fuel. So, Joel’s 5.3-gallon jerry can is more than up to the task of their constant stops. Bonus points to the production team for using a period-correct, pre-safety-spout gas can.

But the problem comes with the fuel itself. Joel is right — , and it breaks down far more quickly than you might imagine. Regular gasoline takes three to six months to decay, according to JD Power, but American gasoline contains an ethanol blend. Ethanol breaks down even faster, taking just one to three months before turning into an unusable mess.

Plenty of fuel stabilizers attempt to address the issue, and some even help out a bit. But none of them will hold fuel stable for 20 years, regardless of how well the fuel is stored. Whether Joel is running the S10's tank dry or siphoning from a parked car, it makes no difference — none of that fuel is going to burn.

Interestingly, later in the show we see military vehicles — which may stand a better chance of working under apocalyptic conditions. Particularly, we see early Humvees, which were offered with diesel-burning V8 engines. Diesel still doesn’t last long enough to be functional after twenty years of sitting, but it’s possible for these vehicles to be running on .

So, next time you find yourself on a post-apocalyptic road trip, leave the S10 at home. Get yourself a diesel truck — you may not find all the fuel you’ll need, but you’ll have a better shot than Joel and Ellie.