GEORGE PLIMPTON, who died in 2003, once joked that he had written a book and a half aboard the Hampton Jitney, the privately owned bus service that chauffeurs Hamptonites who do not have their own town cars or helicopters to their weekend escapes. The math is no prettier now. On a recent Friday afternoon, the ride from the Upper East Side to East Hampton took 4 hours 14 minutes. That works out to an average speed of 24.7 miles an hour.

It is safe to say that the song “Magic Bus” by the Who — “Goes like thunder/It’s a bus-age wonder” — rarely comes to mind on the Jitney.

Still, the bus is such a fact of life in the Hamptons that Hamptonites swap Jitney stories at cocktail parties when the conversation lags: about catching it, about getting a good seat, about buying “value packs” of discounted tickets in the winter. They wonder: Will the bottled water served onboard be cold enough? Will the air-conditioning be too cold?

It is not the Jitney’s fault when the Long Island Expressway is a parking lot, and the Jitney tries its traffic-beating best. It has 50 buses in its fleet and 200 employees on its payroll, 70 of them drivers, but it leases additional buses in the summer. At the busiest times — Friday afternoons in Manhattan, Sunday nights in the Hamptons — it posts coordinators at its stops to see that passengers have reservations and do not board the wrong bus. This summer, it brought in 17 college students from Bulgaria as onboard attendants under a work-exchange program.