For some "in general" information that I maintain my vehicles by.

The real problem is keeping the gas on the "exchange" as the additives deteriorates with age.
I try to add fresh fuel to my tanks, even if I have to pump some out into cans and spread it around with the vehicles I use more.

Gas does this by reacting with air that is in any open space that is above the fuel. As in a cars tank or fuel cans too.

Ground fuel tanks exchange less air due to a more stable temperature environment but have vents that condense vapors if they relieve pressure.

Several years ago, environmentalist wanted all tanks to all be above the ground, to protect our aquifers, due to so many Ma and Pa stores with older steel tanks. As you know many went bye bye.

Addressing the previous issues, they wanted special buildings to protect them from things like open air collisions like cars, trucks, air planes.
Let alone my thoughts of terrorist attacks too. I do not know if that is ever going to gain traction as those stations are closed now.

Petroleum companies got with it and installed fiberglass tanks in the ground. They put in alarm sensors and have to hire inspectors and are tagged with fines if not in compliance. I bet it was expensive but the above ground thing was more expensive with a touch of being insane!
So the environmentalist might be tuning more downward and off onto something else more sensible.

Unless fuel is hermetically sealed up in a container, the fuel will age.
Due to barometric pressure changes outside with every hour of everyday in storage. It cannot be stopped.
A reason is Every car has to have pressure relief valves or vents in order to remove fuel and safely transport the fuel with us "all" around, on down the road.

Now, along with using ethanol in fuel, that has an affinity for moisture, its easier to end up with chances to have more moisture affectively rusting our tanks.
Fuel antifreezes and windshield washer fluids used methanol for years to mix with water.
Fuel Stabilizers, use things like Naphtha to coat molecules to slow the oxidation process down yet it still burns.

A car that's sitting for sale, awaiting repairs or just plain not being used has a ticking time bomb in the system that is going to be a problem. A problem, for any fuel management system, when it becomes to dispensing that fuel correctly at the fine rates required for good fuel economy or emissions.

The bottom line is, if its not driven, it will be passed to any next owner, except the junkyard crusher!
His statement of "condensation" was in part, very condensed! (:-)
Phil