Amazon, Walmart and Kroger gas discounts, explained

Offers at the pump are becoming increasingly popular in retail. Amazon (AMZN+0.96%) recently announced that Prime members can receive a $0.10 per gallon discount at approximately 7,000 BP-affiliated gas stations (B.P+0.65%), including Amoco and Ampm. However, Amazon isn't the only retailer offering fuel discounts – Walmart (WMT-0.40%) and Kroger (KR+1.74%) also offer their loyalty members discounts at the pump.

Here's a look at how these options work and how drivers may be able to save.

Amazon Prime and BP gas stations:

To score $0.10 off per gallon, Prime members must sign up for Earnify, BP's gasoline loyalty program. They must activate the offer on a special Amazon page and link their accounts.

The Earnify app allows members to find a nearby BP, Amoco or Ampm station in the US Discount can then be redeemed by entering the phone number associated with the payment method at the pump or selecting the gas station and pump via the app. Amazon claims that members can save money by doing this $70 annually.

The annual cost of an Amazon Prime membership is $139, about $15 per month, and offers a range of services beyond fuel savings.

Walmart+, Exxon, Mobil and other gas stations:

Walmart+ members may save $0.10 per gallon over 14,000 gas stationsincluding Exxon (XOM-0.09%), Mobile, Walmart, Sam's Club and Murphy (MUSA+0.17%) stations, with a $0.05 discount in Alabama and Oklahoma.

To redeem, members can access member pricing through the Walmart app and pay at the pump or in store. At Murphy gas stations, members must enter a 6-digit discount ID through the app, while at Exxon and Mobil they can scan a QR code before filling up. The savings are reflected in the purchase history.

The annual cost Walmart+ costs $98, about $12.95 per month, and also offers additional benefits.

Kroger and Shell gas stations:

Kroger members earn Gas points for every dollar spent on groceries with a free Kroger Plus Card. At Kroger gas stations, customers can use up to 1,000 gas stations for $1 off per gallon, while at Shell (SHEL+0.79%), 100 points means $0.10 off per gallon.

To redeem points with Shell, customers must press “rewards” at the pump and then swipe their fuel rewards card or enter an alternate ID. Nearby participating locations can be found via the Kroger app.

Kroger offers a free Plus membership. However, for those who want additional discounts on groceries and more gas stations, the grocer offers two additional membership levels: the first costs $59 per year, while the second costs $99 per year. Kroger claims the highest level Save buyers $1,057 per year.