There is no such button.
The gas tank on the 2008 GMC Acadia holds 22 gal..
The gas tank on the 2014 GMC Acadia holds 22.0 gal..
The gas tank on the 2013 GMC Acadia holds 22.0 gal..
The gas tank on the 2010 GMC Acadia holds 22 gal..
The gas tank on the 2011 GMC Acadia holds 22 gal..
The gas tank on the 2009 GMC Acadia holds 22 gal..
The gas tank on the 2007 GMC Acadia holds 22 gal..
The gas tank on the 2012 GMC Acadia holds 22 gal..
There is no button just push down on the gas tank door and it will pop open.
Acadia fuel capacity is 22 US gal or 83.4 litres
bmw x5 fuel tank release button