As a rule, drivers who want to park in a metered space on German downtown city streets have to purchase a prepaid ticket that can easily add up to more than 3 euros ($3.30) per hour in large cities such as Berlin, Cologne, Frankfurt and Stuttgart.

It's annoying to pay any fee at all when it is a matter of a quick stop to get a loaf from the bakery, pick up a prescription at the drugstore or draw cash from an ATM. But not doing so could mean a parking ticket, so many a short-time parker is put in a quandary.

A few German cities have come up with a novel way to solve this problem: an hourglass that people can attach to their windshields or dashboards allowing them free parking while the sand slowly trickles from top to bottom.

Kirchheim unter Teck sells this outmoded but low-cost and effective way of measuring time for 2 euros. The town of 40,000 inhabitants, situated in the foothills of the Swabian Alb, introduced the system in 2013. It's "met with a lot of approval," the city's Andrea Edelmaier told DW.

Inexpensive, practical

Mittweida, a small town in the eastern state of Saxony, also offers the use of the hourglass for quick errands downtown, and Datteln, in Germany's most populous state of North Rhine-Westphalia, is currently considering adopting the hourglass method, too.

Other cities have not latched onto this ancient timepiece, instead offering 15 minutes of free parking with a ticket from one of the regular prepaid vending machines, which Germans refer to as tapping the "Brötchentaste" - the bread-roll key.

Cities need ticket vending machines for this "free parking" version

The city of Cologne offers the option on several busy downtown streets, according to city spokeswoman Inge Schürmann, who said the system had its "advantages and disadvantages."

Depending on the neighborhood, the city loses 28-158 euros in revenue per space per year and, at least in theory, needs more parking enforcement officers to keep tabs, she told DW. In addition, she said, Cologne sorely lacks parking spaces downtown, so a rapid changeover of parked cars is always in the city's interest.