You'd save 10 cents per gallon off of your first fill-up and 5 cents off every gallon after that.
GasBuddy said its card works at 90 percent of stations across the country, including brands like Shell and Mobil. But you won't get the discount at Costco, Sam's Club, ARCO, BJ's Gas and H-E-B stations.
Can I save more after I bought it? Or booked it?
Maybe. Some price-monitoring services will search for a lower price after you bought something, too.
Earny provides refunds if something drops in price after you purchase it. The service covers items bought at participating retailers, such as Amazon, Best Buy, Target, Walmart, Costco Wholesale, Nordstrom, Nike, Kohl's, Macy's, Home Depot and Zappos.
Because Amazon doesn't have its own price protection policy, you must use a price protected card in order to receive refunds on these items, according to the Earny site.
Amazon at one time did offer price protection: If a product's price dropped after you purchased it, you could get a refund for the difference. But that policy doesn't exist anymore, making it useful to use some outside apps, Broida said.
The searching for better deals is done based on receipts in your inbox.
There is a cost: Earny collects 25 percent of the refunds only after you have successfully received a refund.
While the price might seem steep to bargain shoppers, it may not be a bad idea for someone who doesn't have the time to search for a better price and then take advantage of the limited window offered by a retailer who promises to adjust for lower prices, Broida said.
Earny scans your purchases and submits refund requests when there's an eligible price difference.
But are you comfortable giving an outsider access to your emails to scan for your receipts?
Another price monitoring services: Paribus.co (not dot-com) from Capital One, which tracks goods bought online as well as hotel room rates booked through sites that include Expedia, Priceline, Marriott and Hilton. You sign up with the email you use for online shopping receipts and Paribus scans your inbox for receipts from stores that it monitors. Paribus has no service charge.
Broida recommends using price monitoring services after you've booked a hotel for a trip too. He noted that there's a 40 percent chance that your room rate will drop after you book it.
If the price goes down, he said, you can be alerted to the lower price and then cancel your old reservation and re-book in many cases. Travel-related services include: Hopper.com, Pruvo.net, Getservice.com and AutoSlash.com (for car rentals). Is the little extra effort worth it? It very well could be for some budget-conscious consumers. Every dollar can add up over time. ___ ABOUT THE WRITER Susan Tompor is the personal finance columnist for the Detroit Free Press.