The gas tank on the 2012 Volvo XC60 holds 18.5 gal..
The gas tank on the 2014 Volvo XC60 holds 18.5 gal..
The gas tank on the 2011 Volvo XC60 holds 18.5 gal..
The gas tank on the 2013 Volvo XC60 holds 18.5 gal..
The gas tank on the 2015 Volvo XC60 holds 18.5 gal..
The gas tank on the 2010 Volvo C30 holds 15.9 gal..
The gas tank on the 2010 Volvo XC70 holds 18.5 gal..
The gas tank on the 2010 Volvo C70 holds 15.9 gal..
The gas tank on the 2010 Volvo S80 holds 18.5 gal..
The gas tank on the 2010 Volvo XC90 holds 21.1 gal..
17.8 gallons.
As many as the original purchasing customer specified it to hold.