@staticvoidmain wrote:If you are a Costco member, and you don't mind filling up at Costco, then get the Costco card. I save more filling up at Costco with 4% back than I would with any 5% card somewhere else. Their gas is Top Tier anyway. Also, Costco only accepts Visa, which limits your option more (Costco Visa being a Visa).
I don't have the Costco card but I am pretty sure it is 4% at any gas station.
But, yeah, cash back aside, there is a lot to be said for, first and foremost, just finding the lowest gas prices in your area. Also, keep in mind grocery store rewards of $0.XX off per gallon, and apps such as 7-11 or Speedway, etc.
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A lot of the top options have been listed in the various responses, @Ghost117. I'll point you to a complete list, however.
The "Abound FCU Visa" (previously Fort Knox FCU) is the only card I'm aware of that pays 5% or more uncapped on gas purchases. For those who are grandfathered, we also still have members getting an uncapped 5% back on the original Ducks Unlimited Visa. (It's now a 1.5% flat rate cash back card for new applicants.)
For highest CASH returns and if that Abound FCU card is off the table for some reason, I would suggest a layered approach with multiple cards that pay 4% to 5.25% with caps, depending on your spend volume. Here is a previous comprehensive list of the best gas cards that are still relevant. See this thread for that complete list of capped 4% to 5% cash back gas cards. That thread has (14) cards that earn a minimum of 4% back. If gas is a major spend category, there's really little reason to accept a lower return such as the 3% options unless you've already exhausted these.
The one card that is missing from that list is the new Citi Custom Cash that pays 5% on up to $500 per month. It wasn't available at that time. That makes 15! 
@NRB525 wrote:As FinStar asks, what is your gasoline spend? For example, if you max the $500 on the Custom Cash, that's $25 per month back. If you use a 2% card it's $10 back for the month, plus 2% on everything else. So the Custom Cash gets you an additional $15 per month, but then you likely end up juggling multiple cards to try to "optimize" cash back.
The Shell app allows you to pay using PayPal. Link up your primary / preferred PayPal payment card to something like Freedom Flex in the current PayPal quarter, and that will boost earnings.
Many stations ( Chevron in this area ) have Tap to Pay at the pump. Altitude Reserve gets effectively 4.5% on mobile wallet in these situations. Yeah, Annual Fee, but still an uncapped 4.5% if you find stations with tap to pay 
I'm guessing someone with a large gasoline bill may be on the road a lot, so paying for hotel rooms with Altitude Reserve also gets effectively 4.5% earnings.
@Aim_High wrote:A lot of the top options have been listed in the various responses, @Ghost117. I'll point you to a complete list, however.
The "Abound FCU Visa" (previously Fort Knox FCU) is the only card I'm aware of that pays 5% or more uncapped on gas purchases. For those who are grandfathered, we also still have members getting an uncapped 5% back on the original Ducks Unlimited Visa. (It's now a 1.5% flat rate cash back card for new applicants.)
For highest CASH returns and if that Abound FCU card is off the table for some reason, I would suggest a layered approach with multiple cards that pay 4% to 5.25% with caps, depending on your spend volume. Here is a previous comprehensive list of the best gas cards that are still relevant. See this thread for that complete list of capped 4% to 5% cash back gas cards. That thread has (14) cards that earn a minimum of 4% back. If gas is a major spend category, there's really little reason to accept a lower return such as the 3% options unless you've already exhausted these.
The one card that is missing from that list is the new Citi Custom Cash that pays 5% on up to $500 per month. It wasn't available at that time. That makes 15!
Son of a gun! I just spent 45 minutes replying, then I got an error when I hit 'Post'. Not sure I will include links to everything I originally had but here is the nutshell of what I originally posted. 
Nice list A_H in post # 8 of that linked thread. https://ficoforums.myfico.com/t5/Credit-Cards/Summer-2020-best-cash-back-card-for-Gas/m-p/6103368#M1...
I do think it is missing Nusenda, 5% rotating. https://www.nusenda.org/loans-credit-cards/credit-cards/platinum-cash-rewards-credit-card. Especially useful because it is not uncommon for Nusenda to offer 5% CB in two quarters per year - and often staggered quarters from Freedom / Disco-it.
Then I linked a credit union that you didn't list that offers 5% CB gas. Sorry, it is 1:35am and I don't feel like searching again.
Then I listed two CUs that do 5% CB on everything or gas for the first year. Not sure if that even counts?
Then I asked if you are considering AFs or other expenses/hoops. And I used PCM CU as an example. Even if someone could get this card (not sure how easy/hard it is to get?), the hoops required for no AF are, in my opinion, too much and I think most people would just pay the $49 AF, making it, essentially, a 4.XX% card.
Ok, about to click Post again, wish me luck, lol......
@ptatohed wrote:@Aim_Highwrote: ... Here is a previous comprehensive list of the best gas cards that are still relevant. See this thread for that complete list of capped 4% to 5% cash back gas cards. That thread has (14) cards that earn a minimum of 4% back. The one card that is missing from that list is the new Citi Custom Cash that pays 5% on up to $500 per month ...
Son of a gun! I just spent 45 minutes replying, then I got an error when I hit 'Post'. Not sure I will include links to everything I originally had but here is the nutshell of what I originally posted.
Nice list A_H ...
I do think it is missing Nusenda ... it is not uncommon for Nusenda to offer 5% CB in two quarters per year ...
Then I linked a credit union that you didn't list that offers 5% CB gas.
Thanks @ptatohed. Glad to share it.
Dangit, I hate it when that happens ... losing a post I was working on. (I sometimes write in word processor file before posting or save docs to one as I go to avoid that issue.)
Yes, good catch on the Nusenda CU. That would bring the list up to 16. I admit some of those in that list, however, are fenced membership credit unions that not everyone can join. That would include the PCMCU and Aerospace FCU. And it would probably also include the credit union I think you were planning to mention. Was it L&N Federal Credit Union? I've heard of them also but they appear to be very strictly geo-fenced to Southeastern and Northern Kentucky around Louisville including a couple of adjacent counties in Indiana. They offer an uncapped 5% card on gas, similar to the Abound FCU Visa. Counting L&N, however, would bring the list up to 17.
@Aim_High Always an excellent write up! You're setting the bar very high for yourself . I too am in the market for a decent gas card (more than 2%, if I can). Trying to find a good one that also has no FTF is my added pain. I looked through all your suggestions, I don't think any offered no FTF except the PenFed Platinum (I could be wrong). No, I don't expect you to fine tooth that even further for me (unless you're really bored)! I don't mind the leg work .
I would add something to seemingly be advantageous for PenFed. They also cover EV charging fees for 5% back. Albeit, those charges are minimal. I am curious to see how this evolves with the EV market becoming more accessible to the average consumer. Will gas cards be limiting to "gasoline" or will some like PenFed include EV charging stations? I suppose the MCC will come in to play there. Hoping our next car is electric.
@greatscott85 wrote:@Aim_High Always an excellent write up! You're setting the bar very high for yourself
Thanks, @greatscott85! I'm not really in the market for one since I'm pretty well covered. I'm close enough to 5% that I'm not well-served by adding cards. (I have that Citi Costco for 4% and often have either Discover or Freedom for rotating 5%.)
Wasn't much legwork for me so I got your answers on no FTF.
Yes the PenFed Platinum Rewards has no FTF, so that might be your best bet. You also missed the USAA Cash Back Rewards which has 0% FTF. However it's got a $3K cap and PenFed Platinum is uncapped, if that matters. The Huntington Voice card also has 0% FTF. That is capped at $7K per quarter or $28K per year. (The thread link shows $7K annually but that is incorrect.) Finally, the Aerospace FCU card is uncapped 5% on gas with no FTF; however, it's got a very restricted field of membership, according to their website.
Both the Abound FCU and L&N FCU cards have a low FTF but it's not 0%. They are both at just 1% though. And they are both uncapped. So depending on your total spend and your international spend, they might still come out on top of a card with no FTF but a lower rewards or a cap. With one of those two, you'd be getting uncapped 5% domestically and uncapped 4% after the FTF.