Gas Cards, worth it? Which is best?

[bigq]

I was thinking of getting a gas card and just curious if anyone has the inside poop on these. Any gimmics to watch for? Do they really save you money? We offed all our CC cards a while ago, but they look like it could save some money:confused:

[mobldj]

we use the a mex blue,cash back is good,for gas its .5 percent,since nov last year i got a vcation in hawaii worth