No, probably not. But we're talking gasoline/alcohol fuel applications, not Hydrogen and rocket science here.
Modern cars have a sealed fuel system. Older vehicles and lawn/garden equipment have vented tanks (a hole in the cap)
rubber molecules ...Same with gasket materials.
Modern engines use neoprene not rubber.
“But we’re talking gasoline/alcohol fuel applications”
Yes we are, and evaporated Gas/Alcohol molecules are smaller than any gasket/O ring materials used. Over time they leak out right between gasket molecules. Alcohol much faster than Gas because the molecules are even smaller.
“Modern cars have a sealed fuel system.”
Still not sealed. Let a “sealed fuel system” car sit for six months and then smell the gas. It will still be varnish because of evaporation. The cap gasket, O rings, and vacuum lines still leak on a molecular level.
“Modern engines use neoprene not rubber.”
I was referring to tires as a comparative material. Cars use neoprene, nitrile, silicon, urethane, and paper gaskets and seals. All still have larger molecules than alcohol molecules.
An example of this reality would be sealed auto A/C systems. Even though Freon molecules are much larger than Alcohol molecules they still leak out through the O rings and hoses over time.