Your car sits idle more than 90 percent of the time, so why not put it to work as a rental vehicle? With the aid of the Internet and smart phones, it appears to be an idea that's time has come.

Early next year, Oregon will become only the second state in the U.S. to allow people to rent out their cars. In California, which passed legislation last year, personal car-sharing is becoming wildly popular, with what Jessica Scorpio, cofounder of big player Getaround, says are thousands of users in the Bay Area and San Diego.

This is just the beginning. Scorpio says that Getaround (just one of several personal car-sharing companies; others include City CarShare, RelayRides and the London-based Whipcar) plans not only national but also international domination. "People love the variety of cars being shared," she said. "We have Priuses, BMWs and Teslas." Tons of Priuses, judging by the cars on the website. I expect this do-it-yourself approach to car sharing will catch on dramatically and become viral. "It's an alternative to traditional car sharing, but also car rental," Scorpio says. Meanwhile, car sharing itself is also growing dramatically. Car2Go (at right) recently announced a huge fleet of its Smart Electric Drives for San Diego. According to Car2Go's Nicholas Cole, the two-seater plug-in fleet will be 300-strong by the end of the year. "We absolutely need that many cars," he told me. In Austin, Texas, Car2Go has 20,000 members and 300 cars, with more than 5,000 rentals so far.

Personal car-sharing averages $7 to $8 an hour, or $40 a day, but people can set their own rates. This kind of rental demands commitment from both parties, because you have to a) either arrange a rendezvous somewhere; or b) leave the car parked at home or work, where it can be unlocked with the renter's cellphone (a smart card isn't needed).

Want a ride in Pegasus, a very clean. aqua pearl 2003 Honda Civic Hybrid with a friendly owner named Peg Powell? That's no problem, as long as you can afford $7 an hour. It gets 40 mpg, the website says, the renter benefits from an "after-market tape deck," and the Google map will point you to the car's location in Mountain View. "The car was perfect for helping me get to a birthday party across the Bay," posted renter Jason Zucchetto.

If you want something more exotic, there's Nick Kelsey's bright orange 2008 Tesla Roadster in Sunnyvale. You have to be older than 30 and have a clean driving record to snag the keys to that $109,000 car, because it can do the zero to 60 sprint in 3.9 seconds. "It is low and the suspension is brutal," Nick says.

"You will enjoy every minute." But at $50 an hour, it's seven times the cost of that Civic Hybrid. Caveat emptor. "I extended my rental for an extra hour to keep the good times going!" says Bohdi Sansom.

It's interesting how everybody posts their real names, photos and home locations on Getaround. I might worry a bit about security, but Scorpio says there haven't been any incidents. And, she points out, everybody is fully insured - that's the whole point of the enabling legislation.

Transit-friendly Oregon is likely to go nuts for personal car-sharing, which has allowed users to cash average monthly checks of $400 by simply letting people use their cars while they're working. Both houses of Oregon's legislature easily passed HB 3149, which sets insurance rules for and legalizes personal car sharing. The law goes into effect on Jan. 1 and, according to Scorpio, Getaround will launch on the campus of Portland State later that month, then in Portland generally in February.

Getaround claims that it takes nine to 13 cars off the road for every one shared. The company won the $50,000 TechCrunch Disrupt cup last spring, and that's (from left) co-founders Elliot Kroo, Jessica Scorpio and Sam Zaid holding their award.

Getaround will share, with the city of Portland, a $1.7 million Federal Highway Administration grant to be used to recruit the first few hundred car owners. The partners will document early adopter experiences in a three-year study to determine how personal car-sharing impacts auto owners' lifestyles. I'm sure it will reveal that people are much happier with their buckets of bolts. Cars will be at last earning their keep, like the proverbial dog on a treadmill.

Mother Nature Network