As mentioned above, the Amex Mercedes Benz card provides 3x MR Points on gas purchases. What’s also nice about the Amex Mercedes Benz card is that it provides 2x MR Points on dining out. So, if you eat out a lot, that’s a very nice bonus. Lastly, it comes with a 5,000 MR Point sign up bonus on first purchase. However, this card is not to be confused with the Amex Mercedes Benz Platinum card, which only appears to earn 1x MR Points on gas purchases.

The Amex PRG card only provides 2x MR Points on Gas, and you don’t get 2x MR Points on dining. However, you do get 2x MR Points on groceries and 3x MR Points on airfare. If you book your flights through Amex Travel, you can actually get 4x MR Points. So, if you spend more on groceries than you do on eating out, or spend on flights, the Amex PRG may get the nod. Also, the Amex PRG comes with a 25,000 MR Points sign up bonus when you spend $2000 in 3 months.

Another thing to consider is that the Amex PRG card gives a 15,000 MR Point bonus when you hit $30,000 in spending for the year.

Of the Amex cards, the Amex PRG makes the most sense to me. If you spend around $10,000 annually in gas and groceries (2x MR Points), another $2500 in travel (3x MR Points) and can come up with an additional $17,500 in spend for the year (1x MR Points) for the 15,000 bonus… you’re looking at a total of 60,000 MR Points plust the 25,000 MR Point sign up bonus, to yield 85,000 MR Points.

Despite all this, if all you’re looking for a card that will only be used for purchasing gas (and little to nothing else), you may also want to consider the Penfed Visa Platinum Cash Rewards card, which provides 5.0% cash back on all gas purchases.