There are some very cool car apps — such as PlugShare, which gives you the location of home-based chargers whose owners will let you plug in your electric car. And Recargo, which helps those same owners find stations, plan trips and join a community. But I haven’t heard of one that addresses the bane of any traveler — parking. Until now, anyway. Streetline is such a sensible idea that I’m surprised nobody thought of it sooner.

Actually, Streetline’s been around since 2010, quietly building in the background. It’s a smartphone app that aims to free you from the tyranny of endlessly circling the block, looking for an available parking space. Zia Yusuf, Streetline’s CEO, said people spend an estimated 30 percent of their driving time engaged in cruising for parking, and I believe it.

University of California at Los Angeles (UCLA) professor Donald Shoup, a dedicated bike rider and author of "The High Cost of Free Parking," describes the search for a space as “the unstudied link between transportation and land use.” He estimates that people spend an average of eight minutes searching for a space, and you can imagine the cost in terms of lost productivity, exhaust and greenhouse emissions, traffic congestion and more. Cruising, he says, creates “five vehicle miles traveled per space per day.” Over a year, it’s 1,825 miles traveled per curb space.

The psychology of this is interesting. If parking garages cost a lot more than on-street parking, even people with money to burn will circle endlessly looking for the cheaper deal. The obvious solution is to equalize on- and off-street pricing, but that’s probably a bridge too far in a free enterprise system.

Among Shoup’s other points: We subsidize parking for employees but offer no comparable benefit for people who make things easier for everybody by biking or taking public transit. He estimates that it costs $16,600 for a building to add a single parking space, so the least corporate managers could do is offset some of that for the carless.

But that’s another story. Streetline is designed for people with cars and the problem of finding a place to put them. In Los Angeles, for example, Streetline has close to 10,000 small blue sensors embedded in parking spaces. Their sole job is to transmit data as to whether the space is occupied or not. If you’re a commuter with the free Parker app, you can see available spaces on a GPS map, and also parking garages, how many spaces they have and how much you’ll pay for them.

Among the clever aspects of the Android and iPhone app is a timer so you can get back to a parking meter on time, and a filter that lets you choose between on- and off-street spaces. It connects to the phone’s camera so you can take a picture of your car.

The only drawback to Streetline at the moment is that it’s only in 21 locations, and some don’t have the sensors yet — only the parking garage information. But it’s growing, and Yusuf predicts 100 locations by the end of next year.

Cities like Los Angeles that pay for Streetline have access to an online map showing where cars are parked at any given moment. The advantage of this to city planners is obvious, since they can better manage traffic flow. And, Yusuf says, they can also gather valuable data to set time-of-use rates, also known as “dynamic pricing.” If all spaces are occupied at 7 p.m., for instance, that’s when you can charge peak amounts. “There’s no sense charging a lot for parking when there’s no demand for it,” Yusuf said.

Another Streetline revenue stream is parking garage owners, who get access to a customer base in the hunt for its product. Through the app, owners can transmit the availability of spaces and also special rates to get people to pull in.

You don’t have to be Bill Gates or Steve Jobs to see ways of expanding this business. It neatly integrates with restaurants and entertainment offerings — you click on a club or move theater site as you approach the venue and it tells you where there’s available parking. It’s worth paying if the app gets people in seats.

I don’t want to do a commercial here. This is a business, not a public service. Yusuf comes out of software company SAP, where he worked with now-deposed Better Place founder Shai Agassi. “I joined Streetline two years ago,” Yusuf said. “Shai was doing charging, so I thought I would take a crack at parking.” Streetline recently raised $15 million in a venture round and is anticipating another one. Investors include Sutter Hill, Rockport Ventures and Fontinalis.

I’m writing this on a train headed for New York City, where parking space is at a premium. I note with amusement that circling is not above average in New York, according to Shoup’s stats, but that’s likely because so few people are crazy enough to take a car into Manhattan. It’s a public transit city. If I was driving, though, I’d be firing up the Streetline app right now. Here's what it looks like on video:

Related story on MNN: Why free parking isn't free

Jim Motavalli ( @jmotavalli ) writes about cars, technology and the environmental world to anyone curious enough to ask.

Streetline app aims to end the hunt for a parking space
Imagine having your cellphone tell you where to find a parking space in a crowded city. Actually, it's already available — and it's free. Streetline isn't ev