This depends upon the model and year. Wagons have the tank accessible under the back of the car, behind the rear axle. On early 240 wagons, the fuel tank is held by 8 or 10 large bolts and if you are careful to detach the fuel pump bracket on the driver (left) side, the bolts can be removed and the tank can be lowered. I recommend a floor jack to lower the tank without damaging it or ripping the sender wires out of the top.
Coupes and sedans are a different story entirely, most wagons should be similar although some may have additional mounting hardware or other components that need to be uninstalled before the tank can be lowered out.
up to 60 in its tank
My 1982 244 GL tank was 60 liters / 13.2 imperial gallons / roughly 16 U.S. gallons
The gas tank on the 2012 Volvo S60 holds 17.8 gal..
The gas tank on the 2006 Volvo C70 holds 15.9 gal..
The gas tank on the 2005 Volvo XC70 holds 18 gal..
The gas tank on the 2008 Volvo C30 holds 15.9 gal..
The gas tank on the 2012 Volvo C70 holds 15.9 gal..
The gas tank on the 2011 Volvo S60 holds 17.8 gal..
The gas tank on the 2011 Volvo S80 holds 18.5 gal..
The gas tank on the 2010 Volvo XC70 holds 18.5 gal..
The gas tank on the 2013 Volvo C70 holds 15.9 gal..
The gas tank on the 2010 Volvo C70 holds 15.9 gal..