Zipcars are available to licensed drivers over the age of 21, without charging extra fees for drivers younger than 25 as some rental companies do.

“We have not seen that increased risk in any way, shape, or form,” Malloy said of the idea that younger drivers are more dangerous.

At Wellesley College, Zipcar allows students as young as 18 years old to join because the college agreed to insure the younger students.

“For the most part,” Malloy said, “they were already covered under their blanket insurance policies.”

Holly B. Bogle, program manager of Harvard CommuterChoice, helped to arrange the membership discount for Harvard affiliates. She said that Harvard is considering entering into an agreement to provide younger undergraduates with access to Zipcars, but the extra insurance costs could be a problem.

Bogle uses the service herself, and has found it very useful.

“I love the fact that I don’t have to own a car,” she said. “You pay for what you use. You don’t pay insurance, you don’t even pay gas. It’s all included in the hourly rate.”

Darren S. Morris ’05, a senior in Mather House, is another Zipcar user who raves about the company.

“It’s the greatest thing ever. I love it,” he wrote in an e-mail. “It’s the best part about turning 21. Well, almost.”