Lawrence’s Sonic Drive-Ins are looking to cash in on the latest fast-food craze: allowing customers to swipe credit cards for burgers, fries and drinks.

“We love it,” said Kris Gouge, general manager of the Sonic at 1003 N. Third St., which this week received new card readers for all 32 stalls. “It’s something that’s been coming for a long time. It makes things so much easier.”

Sonics in Lawrence, Baldwin and Eudora are among the fast-food restaurants to plug into systems for credit purchases.

McDonald’s has been accepting credit payments since last year, as customers can choose “credit” and pay without having to sign for the purchase. Wendy’s, Taco Bell and other chains also have credit options.

At Burger King on 23rd Street, credit payments have been accepted for more than a year and account for about a third of all transactions, manager Chester Becker said.

“It’s everybody,” he said. “It’s just a lot easier to carry the credit card than it is to carry cash.”

About $22.5 billion of the $140 billion Americans spent on fast food last year went on plastic, according to CardWeb.com Inc., which tracks credit spending. Experts expect such transactions to eat up more than $30 billion this year, after checking in at $12.9 billion in 2003, $6.1 billion in 2002, $3.7 billion in 2001 and $1.7 billion in 2000.

Previous studies have shown that consumers tend to spend about 30 percent more when using plastic in fast-food establishments, according to CardWeb.

Gary Bradberry, of Kearney, Mo., installs a new PAYS (Pay at Your Stall) system at the Sonic Drive-In in North Lawrence. The drive-in's manager said the restaurant has had a spike in credit-card payments since installment.

Sonic previously had accepted credit payments, but had relied on carhops to ferry the cards and receipts between customers and the cash register, Gouge said. And the old credit system used a slow telephone line, which added to the wait for customers and employees.

Now, with the new PAYS (Pay at Your Stall) system, customers can call in their orders with a familiar push of a button — then swipe a card and wait as little as 20 seconds for the payment to clear.

“Now we can hand them the food and the receipt at the same time,” Gouge said. “It probably saves one and a half minutes.”

A new PAYS (Pay at Your Stall) system.

Until this week, the Sonic in North Lawrence had about 9 percent of its transactions handled through credit cards, she said. Now the number has spiked to “15 to 20 percent, overnight,” while other area locations have seen as many as 35 percent of purchases being completed with plastic.

The restaurants would have turned the corner earlier, Gouge said, but officials wanted to be sure they could handle the transition.

“Technology changes every single day,” Gouge said. “It’s nice to upgrade every now and again — it’s good for the customers and it’s good for the employees.”