Technology Makes Car-Pooling Safer and Easier The annual ritual of piling into the car for the great American summer road trip has a new twist as more travelers are inviting strangers along for part of the ride. Long-distance travelers as well as commuters are connecting on sites like Zimride.com, Ridejoy.com, Avego.com, Nuride.com, Rideshare.com and eRideShare.com. This summer, a German company with a quintessential American name, Carpooling.com, will try to break into the United States market with a trial run in the Northeast. In June, the company announced that 30 million rides had been offered through its 10-year-old network, which now has 3.8 million registered users. Ride-sharing and car-pooling, it seems, are having a moment in the United States after many fits and starts. "It's been a tough sell in the U.S. for a long time," said David Burwell, director of the energy and climate program at the Carnegie Endowment for International Peace. A lot is due to not only the fact that people have different places they want to go, but also safety and other concerns about going into a car with strangers. What is different now, Mr. Burwell said, is the advancement of digital technology and social networking, "which removed a significant amount of barriers." To that end, eRideShare, which was started in 1999, is testing a mobile app this week for iPhone and Android phones. "I see a lot of new entrants this year" as well as new technology, said its founder, Steven Schoeffler. I think it will be a very interesting time for ride-sharing. The sites vary in the process of matching drivers with passengers, security protocols and how payment is calculated and made. Some sites allow participants to settle on the cost of a ride; others charge by mile traveled. The profit-making sites take a percentage of the fee charged to riders, but it's free to sign up for the service. Proponents of ride-sharing say that, by design, it is an effective way to reduce congestion and greenhouse gas emission, as well as to save money on gasoline and car maintenance. America's love affair with cars is not fading into the sunset anytime soon. By Sunday, 42.3 million Americans will have journeyed 50 miles or more from home during the weekend after the Fourth of July, according to AAA estimates. That is up 5 percent from last summer. On any workday, however, most drivers are riding solo. The percentage of people car-pooling has hovered near 10 percent for several years, according to Census survey data. About 5 percent of commuters use public transportation, and 76 percent drive alone. "The reality is, we do it because it happens to be the most convenient best option for us," said Paul Steinberg, director of Americas at Avego, a multinational transportation company that is conducting several real-time ride-sharing tests in the United States. "We are trying to convince 85 percent of the population to give up their car - not every day, but a couple of days a month - and pick up someone or share a ride," Mr. Steinberg said. It's a big challenge; it's harder in the U.S. than other geographies. American culture is partly the reason, he said, as is sprawl and subsidized gasoline. In Sonoma County, Calif., Avego is helping to run a private-public nonprofit program called WeGoRideShare.com. Two testers, Monika Loose and Cyndi Mills, employees of the Sonoma County government, found each other through a ride board on the Web site and have recently shared rides a few times a week. Ms. Loose is a passenger and helps pay for gas. She drives from her home to a nearby Park and Ride lot, where Ms. Mills picks her up. Together, they can ride in the high-occupancy vehicle lane, which reduces their commute time. "For me," Ms. Loose said, "I'm not an everyday car pooler, maybe three days a week. I like to have my car other days to do other errands. That also works for Ms. Mills, who says the few days add up and help defray her monthly gas costs. Because she is often transporting her children, she said, "I don't want people dependent on me every day." Tara Weingarten, founder of the automotive site vroomgirls.com, said ride-sharing could work regionally for some commuters but faced resistance in car-centric places like Southern California, "where drivers are used to being cocooned in their private auto bubbles padded with comfy seats, satellite radio, climate control and privacy, where they don't have to make chitchat if they're not in the mood." Even so, companies that promote the exchange of rides are joining a wave of so-called collaborative consumption sites that use social networks to build communities like Airbnb.com, for finding a place to stay, Swap.com, for exchanging goods, and TaskRabbit.com, for outsourcing tasks and errands.