The roof of the Mississippi Market co-op at Selby and Dale in St.Paul sports a 10-panel solar collector.
The electricity goes to a box attached to a lamppost in the parking lot. A cord comes out of the box; at the other end of the cord is a normal three-prong plug, and it's plugged into the back end of a Prius.
"The battery is installed in the spare tire wheel hub," says Chris Duffrin, who's taking me for a spin in the Prius.
"You just unplug the plug back here, and you enter the car just like the rest of our cars -- you use your key fob to scan in. That pops the locks open."
The key fob is programmed with your account information. It gets you in the car, and tells the HourCar computer when you're using the car and when you bring it back. The key to the Prius is in the car.
When Duffrin starts the car, there's just a quiet whirring. The computer screen on the dashboard displays all kinds of information, including data on the most recent trip.
"There's the trip I just took to South Minneapolis for a meeting," he says. "We went 18 miles round-trip; we got 94.8 miles per gallon. With our plug-in we often get in the 90s, and at times we're running over a hundred miles per gallon."
There's still an engine in the front, and it kicks in when you accelerate quickly. But the primary power is delivered by the battery. These vehicles get about twice the mileage of a standard Prius.
Duffrin is Executive Director of the nonprofit Neighborhood Energy Connection. HourCar is one of its projects.
"You can get some trips in this car where you are literally emitting no carbon," he says.
It costs about $10,000 to add the battery, and the solar collectors cost about $18,000. "What we're trying to do is demonstrate that, when those prices start coming down, this is something people can do," Duffrin says. "And not just for themselves, but if they share a car and share those costs, then this can become a really efficient, clean way of traveling."
HourCar started three years ago. At first, the people who joined were mostly motivated by concerns about the environment, Duffrin says. But now people want to save money on gas. Membership grew by 70% in the last year. Still, it's a tiny number: there are 650 members. They share 16 cars, parked at about 15 locations around the Twin Cities.
The payment plans include a monthly fee and a charge per hour and per mile.
HourCar is helping just a tiny handful of Minnesotans reduce their carbon footprint. But their individual choices are moving the whole society toward better answers, according to J. Drake Hamilton. She's a climate change expert at Fresh Energy.
"When companies and policy makers see that people really want better options out there -- they want smarter ways to get to work, and they want cleaner cars -- that's a time to step in and say, 'Okay we're raising the bar, we're keeping climate and people's pocketbooks in mind, and we're making better choices available everywhere,'" says Hamilton.
I took another ride with Sarah Miller. She joined HourCar in May.
"I just felt like I had gotten really wasteful, and I would drive to Target for toothpaste, and I'd spend more on gas than toothpaste, but I just didn't seem to be changing my behavior."
She decided to get rid of her car.
"I was just petrified as to how I was going to get around, but surprisingly it has just been so easy."
She takes the bus to her job in White Bear Lake and uses HourCar for groceries and to run errands and visit family members off the bus line. She figures she's saving about $200 a month.
And she loves the burgundy HourCar, with its computer screen and controls on the steering wheel.
She's a little nervous about relying on the bus and HourCar in the winter. But she wants to make it work. She feels freer.
"I used to worry about my car all the time: what new bill would come up, what would gas be next week, and it allows me to let go of all that," she says. "It's made a remarkable difference."
She's returning this HourCar to a ramp in downtown St. Paul.
"Here we are, and there's a sign that designates where to park."
She makes a quick check of the car to make sure it hasn't been scratched, and "fobs out".
"I put just put my key fob that's on my key chain onto the windshield of the car, by the key-fob box, and it locks the car."
Two blocks from the ramp, Sarah Miller catches her bus for home.
Next time she uses an HourCar, she'll probably get the one at the Mississippi Market, the one that's plugged into the sun.