Speaking from the industry:
It's merchant specific, depending on their terms with visa/MC/amex. If you ask the merchant they are generally ill-informed and blame the bank, if you ask the bank they blame the merchant. There is a way to clear the hold early, but it's a hassle and usually only done when a power outage caused a pump to not send a final amount to the bank/network.
Holds(preauths) vary between $1, $75, $100, and $125. Amex is almost always $100. MC is almost always $1. Visa is usually $1, but can be $75-100 rarely. Debit cards can vary widely.
As far as WF Propel, it's an Amex network so it falls into the usual $100 preauths for at-the-pump gas. It takes longer for pending transactions to post on this specific card as well.
If you want to avoid the $100 preauths on Amex you can pay inside for a set amount, if the card has a lower limit this is generally less hassle than waiting for it to post and release available credit.
I think that it may be more than card network specific too. I think it's a combo of network, issuing bank, and specific merchant. I use all of my cards for gas at a wide variety of stations. My Amex, Disco, and DC always have a hold for $1 on them, then the final amount posts within a couple of days depending on the card, and which station I used. Then after that, the $1 hold is lifted again. I have never once had anything higher than $1 placed on any card. My Cap1 does exactly the same thing as the OP mentioned. It gives a preapproved amount of $1, then almost immediately posts the correct final amount and the $1 falls right off. It was always something I liked about using my Cap1 at the pump. It's weird how this one seems to vary so much between everyone.
@Ficoproblems247 wrote:I think that it may be more than card network specific too. I think it's a combo of network, issuing bank, and specific merchant. I use all of my cards for gas at a wide variety of stations. My Amex, Disco, and DC always have a hold for $1 on them, then the final amount posts within a couple of days depending on the card, and which station I used. Then after that, the $1 hold is lifted again. I have never once had anything higher than $1 placed on any card. My Cap1 does exactly the same thing as the OP mentioned. It gives a preapproved amount of $1, then almost immediately posts the correct final amount and the $1 falls right off. It was always something I liked about using my Cap1 at the pump. It's weird how this one seems to vary so much between everyone.
Yes, it's really interesting to see the variance in experiences. The Propel card is the first time I've ever seen such massive holds placed against credit limit. I've been using various cards for years, including previous AMEX, and never noticed this sort of thing. But of course, I had to run my test with the Cap1 this morning to be sure I was recalling things correctly....and I was. More reasons to like them now. 
I have yet to use my Propel at a gas station, but all of my other Amex Cards (amex and ncfu) place a $1 hold. Debit cards have placed larger holds.
@mikesonthemend wrote:I have yet to use my Propel at a gas station, but all of my other Amex Cards (amex and ncfu) place a $1 hold. Debit cards have placed larger holds.
Mike, make a point to try a gas station. Once you do, be sure you look under your temp authorizations (dropdown above your posted transactions) in your app for the $100 hold. Let us know!
My FNBO Ducks Unlimited Visa does this everytime at every gas station. Since it's my dedicated 5% gas card, I notice it. Only ever a $1 hold though.....don't think I've ever seen a hold larger than that. I wonder if it's region specific to have such high holds that you guys have mentioned? A $100 hold each time would be pretty aggravating.
On Deck: No Plans Currently
@Taurus22 wrote:My FNBO Ducks Unlimited Visa does this everytime at every gas station. Since it's my dedicated 5% gas card, I notice it. Only ever a $1 hold though.....don't think I've ever seen a hold larger than that. I wonder if it's region specific to have such high holds that you guys have mentioned? A $100 hold each time would be pretty aggravating.
It's very aggravating. Imagine my shock when I got a notification for a $350 purchase at QuikTrip! For a GAS HOLD!!! 
It wouldn't be so bad if it automatically dropped off the next day, but they will tell you 5-6 business days and that's what I've been seeing. That part is terrible.
I used to get a $100 hold on my Delta amex. Then one day it stopped and it's updated in real time now.
