Up to 17.4 gallons.
138 Imperial gallons, approx.
Up to 4,318.26 US gallons of water.
You can fit 8 gallons in 8 gallons.
In the whole car or in the gas tank?
Yes, you can make it fit with major modifications.
15.5 gallons
12,960 US gallons will 'fit' in 1,733 cubic feet.
About 20 gallons
The number of barrels that can fit in a cylinder depends on the dimensions of the cylinder and the barrels. The formula to calculate the volume of a cylinder is πr^2h, where r is the radius of the base of the cylinder and h is the height. By dividing the volume of the cylinder by the volume of a barrel, you can determine how many barrels can fit inside.
A 2012 Honda Fit has a fuel tank capacity of around 10.6 gallons.
12 liters is about 3.170 US gallons.