According to my Chilton's Auto Repair Manual :
A 1970 Ford Mustang has a ( 22 U.S. gallon ) gas tank
16.0 Gallons
16 gallons ( according to the 2012 Ford Mustang Owner Guide )
15.7 gallons
15.4 US Gallons
16 gallons
According to the 2006 Ford Mustang Owner Guide : ( 16.0 U.S. gallons )
16.0 U.S. gallons
15.4 U.S. gallons
16.0 Gallons
20 gallons
16 gallons
16 gallons