The ExxonMobil Speedpass was the first radio frequency device to automate payment at the gas pump--and it's owned the market ever since. But Wednesday, Phillips 66 Co. will begin testing its own RFID system--the PhilPASS--at 20 company-owned stations in the Kansas City area.

Shell Canada already has debuted its easyPAY system in six cities north of the U.S. border, while Shell in the United States has rolled out easyPAY in the Indianapolis and Cincinnati markets.

All three systems come from the same supplier, Texas Instruments Inc., and work the same way. Pre-registered customers simply wave a one-inch transponder in front of an antenna to identify themselves and charge their purchases to a credit card.

ExxonMobil has close to 5 million customers now using the Speedpass to pay for gas and goodies at 3,500 Mobil stations, and it's rolling out the technology at 1,800 Exxon stations as well.

The RFID market has grown beyond gas stations to include fast-food retailers. McDonald's has been testing various forms of RFID devices, including the Speedpass, in pilots across the nation; and Tricon Restaurants' Kentucky Fried Chicken and Taco Bell outlets are beginning a test of RFID technology from independent supplier 2Scoot.

Waving a wand is quicker than swiping a credit card and cleaner than anteing up cash--a definite selling point to customers who are about to eat a Big Mac with their hands, believers say. And because these micropayment systems aggregate charges until they hit a given amount--usually $25--before posting them on a credit card, they cut the credit cost to the merchant from about 30 cents to about a dime.