It might be, but not for me. When i was going to trade in my first Vibe for a different Vibe, I tried and failed to do so, and ended up trading in a car with a nearly full tank of gas. But just because I couldn't do it doesn't mean its not possible
I figure that's going to be the verdict. We'll see if anyone else chimes in. I keep my tank full all the time, and got thinking that it would be nice to have access to that gas in an emergency for my gas generators.