If I use my Sheetz card to pay for gas, why not text me the car wash code with an email backup if the receipt? Saves paper, makes it easy to search for that code you didn't use yet, and avoids the printer-out-of-paper issue.
I, as many people do, use the car wash that available at our local sheet and I think it would be great to have a program that you buy so many washes and get one free or wash upgrades for free, fill-up with gas 10 times and get a free wash, etc. Reward points could be given in store when use your My Sheets Card as well.
I had been using Sheetz very frequently however an Exxon gas station has started to offer 20 cents off every gallon of gas if you buy a car wash who's minimum price is $6.00. If Sheetz offered a program such as this I would come back to using Sheetz.