If your car is going to sit in a hot garage for a month and a half, is it wise to have the gas tank full, half full, or a quarter full of gas?

You can put a battery tender on it and fuel stabilizer in the tank and be perfectly fine.

Actually...I would guess full because that would cut down on condensation as the temperature fluctuates... you wouldn't want to come back to find water in your gas.

how hot of a garage? a month and a half isn't super long. I don't think it'd really matter.

I'd say a quarter.lots of room for any pressure and breathing.The bottom of the car I'm sure is still a little cooler anyways.

I'd be more worried about the battery, heat drains those bad boys like nobody's business.

Put some gasoline conditioner in the tank. Gasoline can go bad if left for a while.

half so it doesn't die of starvation

it doesnt matter