U.S. mobile banking apps already let customers preorder cash to take out at the ATM and make appointments to see bankers in the branch. Now a Polish bank is raising the time-saving stakes.

Idea Bank has introduced a free feature for small business customers that lets them order a car with a built-in cash deposit machine to come to them within an estimated arrival time of 30 minutes. Like in the popular Uber and Lyft car-hailing services, a bank customer can look at the standalone app to see a map that shows where the driver is.

The initiative comes as banks in the U.S. struggle to design apps for small business customers for numerous reasons, including the challenge of identifying which of their retail customers are business owners.

Currently, one car, a BMW, is servicing the Warsaw area and the bank will have two Fords circulating within the next two weeks. The Fords will have ATMs in addition to cash deposit machines (the latter accepts but does not dispense money). Eventually, Idea Bank, which counts about 200,000 entrepreneurs as customers, plans to have 40 cars driving to them.

"For the small business owner, it's an attractive concept," said Bill McCracken, chief executive officer at Synergistics Research in Atlanta. "The cash challenge is not one technology has readily solved." In the U.S., he said, small business owners use the branch and ATM more than twice as frequently as retail customers — and the motivation for 80% of small businesses' visits is to deposit money.

According to Idea Bank's research, one in three business owners in Poland only transact in cash. And 80% of the respondents told the bank they deliver the money to the institution in person — which poses security concerns. The bank also said its customers rarely employ staff and are small-scale companies.

The initiative is meant to help build the image of a convenient and pleasant bank, Idea Bank said. Beyond the branding ambition, it also sees the app as helping to digitize money in a country where entrepreneurs often transact in cash for everyday payments, and in turn, help them improve their credit ratings. It also sees the car service as a way to attract new customers.

Katarzyna Siwek, the public relations director for Idea Bank, said the bank is, in the longer term, hoping to create something akin to Family Frost, a European equivalent of Mister Softee or Good Humor. Just as the ice cream trucks' jingles draw people out to the streets, the bank hopes entrepreneurs will see others using its service and decide to sign up with the bank.

"Neighbors follow neighbors," said Siwek in a Twitter conversation with American Banker. "We hope that once you order the mobile [cash deposit machine] other entrepreneurs will follow you, and all the entrepreneurs on a certain street will use the service in a few months."

A consumer has to be a customer to use the service. The app requires one to sign in with the bank's login credentials to use.

McCracken views PNC's pop-up branch as a cousin to the Polish bank's initiative. The pop-up branch, which was introduced in Atlanta in 2013, has been used to get the Pittsburgh bank brand visibility in a region where it had a limited presence. It's not on wheels but it can be — and has been — towed to cities like Chicago.

Bob Meara, senior analyst in Celent's banking group, views an on-demand cash courier service as disruptive. Typically, merchants would need to take time out of their day to deposit the cash at a branch or pay a fee for an armored courier that runs more like a bus line than a taxi.

"If you want something quickly, [there could be] extraordinary surcharges," Meara said.

Idea Bank's car service, which is available to order from 8:00 a.m. until 10:00 p.m. with professional bodyguard drivers, is free for customers, though the bank is considering charging a fee for entrepreneurs who withdraw money from a card issued by another bank.

The institution's new service exemplifies two broader trends: ever-more companies are offering on-demand services and banks continue to make unexpected alliances to compete in a digital age. In this case, Idea Bank partnered with iTaxi, the popular Polish app for fast and direct cab booking, which created the mobile booking app for Android and iOS.

McCracken said banks interested in doing something similar would have to evaluate the costs and the security risks. If manned by one person, the vehicle could be a target for thieves looking to commandeer a vehicle flush with cash, for example.

That aside, industry observers envision a day when more banks will bring services to customers' physical locations, and at the very least, offer them a ride through the app.

"I could imagine summoning a loan officer to come to the home," said Jeremiah Owyang, founder of Crowd Companies, an outfit in San Francisco that educates large, established companies about startups. "The potential exists."