Almost one-half of all 18- to 34-year-old drivers are driving less, and nearly two-thirds would drive less if alternative transportation options were available, according to an independent study commissioned by Zipcar Inc.

The study of licensed drivers conducted in October by KRC Research revealed that 45 percent of Millennials (ages 18 to 34) said they had consciously made an effort to reduce how much they drive and 64 percent would drive less if alternative options, including public transportation, car sharing or convenient carpooling (ridesharing), were available in their area.

When only the 25 to 34 age group is considered (excluding college-age students) 67 percent say they would drive less if other options were available.

Concerns about the cost of car ownership outweighed environmental concerns, but Millennials were more likely than other age groups to drive less to protect the environment, with nearly half (45 percent) saying they drive less to protect the environment compared to 39 percent of 35 to 44-year olds, 37 percent of 45 to 54-year olds. Those over 55 seemed more aligned with Millennials with 42 percent saying they drive less to protect the environment.

The study included 1,025 adults age 18 and over, of which 966 were licensed drivers. It was conducted between Oct. 7 and Oct. 11, 2010, and utilized quotas for age, gender and region based on the national Census.

To view the survey results, click here.