WASHINGTON — Think of the typical city bus, and you're likely to picture old vehicles with hard seats and noisy brakes that belch diesel fumes as they jerk from stop to stop.

Transit agencies want you to take another look. They're rolling out more attractive and comfortable buses, convenient express routes and even on-board Wi-Fi.

High gas prices and a tight economy have made all kinds of transit, including buses, more popular. In the first three months of 2008, 2.6 billion trips were taken on public transportation in the U.S., a 3 percent increase over the first quarter of 2007, according to the American Public Transportation Association. Bus ridership increased 2 percent to nearly 1.5 billion trips.

Buses may lack the hipness of subways or light rail, but they are the best hope for accommodating large numbers of new riders quickly and affordably. To harness the increased demand for mass transit, officials are turning to new ways of delivering and marketing their bus service.

Ted Mann, an Arlington, Va., resident, has been a regular bus rider since totaling his car a year ago and has noticed the improvements.

Mann, 66, said the Washington area's extensive transit service has meant he hasn't felt compelled to buy a new car. Still, he can testify to the image problem that buses face.

"The other night I was with a group of people, and the fastest thing to do was to get on the bus. Some of these people had never been on a bus — as if this was some awful low-class way," he said.

Nationally, bus riders tend to be poorer than rail passengers. According to a 2007 national study by public transportation association, 21 percent of trips by rail are made by people with household incomes less than $25,000, compared with 43 percent of bus trips. On the other side of the spectrum, 30 percent of rail trips are made by people with incomes of $75,000 or higher, while only 12 percent of bus trips are.

Metro, the Washington region's transit agency, hopes a makeover will help buses' public relations problem. This month the agency is introducing new buses with a modern red and silver color scheme, cushioned seats and sound-deadening floors for a quieter ride.

"People who wouldn't normally take the bus — they can see this beautiful piece of art here and want to take public transportation," said Milo Victoria, Metro's assistant general manager for bus operations.

Elsewhere, transit agencies from Chattanooga, Tenn., to Cincinnati to Oakland, Calif., have introduced Wi-Fi on buses, particularly those on longer commuter routes. Metro plans to make Wi-Fi available at elaborate new bus shelters in Arlington, which will also feature heated seats and electronic signs with bus arrival and departure information.

And transit systems are looking for inexpensive ways to make bus trips faster. Cincinnati's Metro received permission this month to make permanent an arrangement that allows buses to travel in the left shoulder of I-71 when traffic is heavy. Other systems use technology that keeps traffic lights green when a bus approaches.

Transit systems are also adopting more fuel-efficient alternatives to regular diesel buses, helping insulate them from rising fuel costs while also providing another selling point for potential passengers who care about the environment.