Hello mcmillan and welcome to the forums!
Let me start by saying that I personally would not recommend getting a gas card. I find them very limiting as you can only get gas with them, and usually you can only get one brand of gas. If you do decide to apply for one, I would go with a gas card that is issued by GE (also known as GECRB), for example the Chevron/Texaco card. I believe GE cards are easier to get. I would also try to get a card that’s not only a gas card card but that can also be used as a regular credit card. You’ll get more out of it and it will be easier for you to establish good credit history if you can use it anywhere.
Shell, Exxon/Mobile are issued by Citi and they are known to be picky, so while you are building or rebuilding I would stay away from Citi unless you want to try their secured card. Which brings me to: why not get a second secured card? Bank of America offers a cash rewards card (3% cash back on gas). After one year, if you treat it right, it will be unsecured and you will be given your money back. I’ve had one for about 9 months and it’s now my main card, my capital one doesn’t get used that much anymore since I’ve had the BoA secured cash rewards card. It’s due to graduate this November.
I have a paypal line of credit which I’m pretty happy with. It’s issued by GE as well and it was pretty easy to get, and from what I hear their credit increases are pretty generous and you can apply for one every four months or so (I’ve had mine for two months so far so i’ll report back in a couple of months). It works great for me as I use eBay and paypal a lot, but I can also use it as a regular credit card when linked to my paypal debit card. If you are lucky when you apply, you’ll get their regular credit card which is also a cash rewards card. I applied and only got their line of credit. But then again, I buy a lot of stuff from eBay and use paypal to pay for some services. If you use paypal a lot, I recommend it!
Are you building or rebuilding? Do you have a lot of baddies on your reports? Have you applied for a lot of cards lately? How long have you had credit for and how many cards do you have? All these answers will heavily influence whether you have a good chance to be approved for new credit or not.