The shuttles may not be able to lift Google’s stock price, but they have struck a chord with employees.

“It’s the most useful Google fringe benefit,” said Wiltse Carpenter, a 45-year-old software engineer. Mr. Carpenter has been with Google only a few months, but before that he had commuted from San Francisco to the same Highway 101 exit since 1992, having worked at Silicon Graphics and Microsoft, two Google neighbors. “It’s changed my quality of life,” he said.

That sentiment is not surprising. Even Googlers have to worry about the area’s high real estate prices, which have sent families to the outer confines of the region in search of cheaper housing. And the hopping cultural and social life of San Francisco remains a magnet for young workers, even though the commute to offices in Silicon Valley, some 35 miles to the south, can take well over an hour. A recent survey showed that traffic was the No. 1 concern for the area’s residents — for the 10th year in a row.

But on a rainy winter afternoon, as some 20 Google employees hopped onto the 4:40 p.m. back to the Mission and Noe Valley districts of San Francisco, those concerns seemed distant. The shuttle merged onto Highway 101, made its way across three lanes packed with slow-moving vehicles and into the carpool lane, where it began speeding past hundreds of commuters.

Inside, most riders appeared to abide by the shuttle’s etiquette rules. Cellphone conversations are allowed if they are work-related and sotto voce. But loud personal calls are definitely out. In fact, except for a couple snuggled together, no one sat on adjacent seats. Many took out iPods or laptops and worked, surfed the Web or watched videos.

“People tend to be quiet and respectful that this is people’s downtime,” said Diana Alberghini, a 33-year-old program manager.

Google will not discuss the cost of the program, which it operates through Bauer’s Limousine, a private transportation company in San Francisco. But the shuttles appear to be having the desired effect on recruiting. Michael Gaiman, a 23-year-old Web applications engineer who lives in San Francisco and was recently hired, said he turned down an offer from Apple before accepting the job at Google. “It definitely was a factor,” Mr. Gaiman said of the shuttle.