Apple Pay has landed another major supporter in ExxonMobil. Using the company's Speedpass+ app, iPhone users can use Apple's mobile payment service to pay for gas and a car wash at over 6,000 Exxon and Mobil gas stations across the U.S.

ExxonMobil, which lost its status as the world's most valuable company to Apple in 2011, is by far the largest supporter of Apple Pay so far. But to make this work, the company won't be adding compatible payment terminals to its pumps.

"Anything that involves the pump from a hardware point of view takes years to deploy and is extremely expensive," Bryant Russell, Americas program manager for mobile payment and loyalty at ExxonMobil, told CNET.

Instead, it will focus on making Apple Pay payments available on the software side through its existing Speedpass+ app. The app uses GPS to find your location when you're at a supported gas station, than allows you to pay for your fuel before getting out of your car.

"You select the pump number and confirm the purchase using the iPhone's Touch ID fingerprint reader," explains CNET, which received a demo of the technology in action.

"In places where geolocation doesn't work well, you can scan a QR code, or a customized symbol you pick up with your phone's camera, at the pump or search in the app for your location."

Once you've made the transaction, you have about 45 seconds to start fueling your car before you have to start over. You will be issued a receipt at the pump, and you can view your purchase history inside the Speedpass+ app.

Apple Pay is available at 6,000 Exxon and Mobile stations throughout the U.S. now, and ExxonMobil plans to add another 2,000 by mid-2016. Almost all of the 10,000 locations will be supported by the end of this year.

As for Android Pay, Samsung Pay, and others, ExxonMobil has no plans to support those in the Speedpass+ app just yet — despite it being available on Android.