Depends on the year/make/model, but in general they range from 13gallons-20gallons, most of them are in the 15-17 range.
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
12 liters is about 3.170 US gallons.
about 18 gallons
You can fit 752.32 gallons of fluid in a cylinder that measures 4 feet in diameter and 8 feet in depth.