Drive-up banking seems out of place in today's high-tech world, conjuring up images of customers tossing driver's licenses, checks and deposit slips into pneumatic tubes that blast off to distant tellers.

Yet drive-up banking remains popular with consumers across the U.S. who line up in their cars, perhaps unable to turn off that latest pop tune or unwilling to unstrap young children and lug them into the branch.

"It's convenience and not having to get out of your car," said Genie Driskell, chief operating officer at Synergistics Research.

Still, preserving the service is costly for banks, and it presents security issues and other hassles for customers. Some banks have added a dose of modernization — the mobile phone — to the drive-up banking formula to remove some of the paper (think deposit slips) and plastic from the process and to speed things up.

The idea stems from other experiments. Institutions are increasingly testing use of phones to authenticate customers and let them preorder transactions. The feature is viewed as a way to eliminate security threats like skimming cards at ATMs (including the drive-up ones), tie disparate channels together, speed up transactions, promote use of mobile wallets and give customers more control.

In the most extreme example, a Polish bank is delivering ATMs on wheels to small-business owners who request the service through a mobile app. Two banks based in the Chicago area, Wintrust Financial and BMO Harris Bank, are among the financial institutions that let people preorder cash at an ATM through a mobile banking app. Wintrust has reported that people enjoy it, and BMO Harris told American Banker its customers have been happy with the new service.

"We don't disclose usage statistics, but we're very pleased with what we've experienced when it comes to usage to date," a BMO Harris spokesman said.

But most recently, Wells Fargo, which already lets customers book appointments with bankers at the branch through digital channels, wrapped up a pilot that would modernize its drive-up banking by tying it to the smartphone.

The drive-up banking pilot involved letting employees use a mobile app to order a transaction ahead of their arrival at the drive-through line or in a branch. Unlike Wintrust's and BMO Harris's approach of using QR codes, Wells' software spits out one-time codes that testers call out to tellers to authenticate themselves. In the test with employees, the codes expired at midnight the day a person preordered a transaction.

Miranda Hill, who manages Wells Fargo's Digital Labs, says it is the banking equivalent of the Starbucks app feature that lets consumers preorder items and pick up them up in express lanes at the store. But unlike preordering a latte, customers are informing the bank they want to deposit a $1,000 check or get back $250 in cash. Once the customer gives the person the code, the data will show up on the teller's software. And, voila, no need for a driver's license — a document that can hold a photo several years old, challenging the teller to check if the photo matches the person in the window.

Wells' test is to designed to be more secure and a faster way for customers to identify themselves at drive-up teller lanes and potentially within its stores. All told, Wells has 14,000 drive-up banking lanes across 4,000 locations. Now, the San Francisco bank is assessing feedback from the pilot conducted earlier this year to decide whether to commercialize the experience.

Synergistics' Driskell said she could see such a feature particularly benefitting small-business customers who are "always into trying to save time as much as possible."

Broadly, the trend toward preordering services in banking could translate into other areas like booking financial advisors in the branch. Wells, Regions Financial and a number of other institutions already make a book-a-banker available to consumers through digital channels.

TimeTrade, one of the vendors that sells such booking software to banks, said institutions are increasingly emulating retailers like Apple to deliver shorter wait times.

"It's the now economy," said Mike Lewis, TimeTrade's chief marketing officer. "People are absolutely not used to waiting. They don't want to wait."

And for banks, connecting channels to expedite a service and other benefits is expected to become increasingly important.

"Omnichannel is a huge priority for Wells," Hill said.