PEDAL-ING SOLUTIONS: Doug Hamilton with his daughters, Sarah age 9, and Beth, age 4. IMAGE: LEAHNASH.COM

When you’re joyful that gas has dropped to about $4 per gallon, it’s not hard to figure out why people are giving up on driving.

But how easy is it to get rid of owning your car for good?

One way to find out is by checking in with an ongoing promotional stunt by Zipcar. The world’s largest car-sharing company, Zipcar has more than 300 participants in Portland and nine other cities going on a “low-car diet”—living without their car for a month.

WW has tracked two dieters since the challenge began on July 21—Doug and Janet Schmidt-Hamilton, two working professionals in Northeast Portland’s Hollywood neighborhood. They have a 9-year-old daughter, Sarah, going into fourth grade, and a 4-year-old daughter, Beth, attending preschool.

Doug and Janet, both 43, decided to give up one vehicle—a 1989 Toyota 4x4 pickup—two years ago to reduce their environmental impact. Now they’re working to get rid of their last car—a 1998 Honda CR-V. They consider the Zipcar challenge a way to jump-start that goal of lessening their environmental impact and providing an example for their kids.

“I’ve always believed that cars are the root of all evil,” says Doug, an architect whose work is four miles from home.

Like all the low-car diet participants, the Hamiltons got 30 days’ worth of TriMet passes and $100 in Zipcar credit.

The first week of the challenge the family traveled 60 miles on bike and 15 miles on foot, and used mass transit or carpools for other commutes.

Before the challenge began, Janet calculated the family was driving about 900 miles per month in their Honda, which gets about 26 miles per gallon. And even though they own the car outright, they were spending $400 per month to drive it.

“Are you sure about that?” Doug asked his wife.

“I’ll show you the math,” said Janet, the self-proclaimed coordinator of the family.

“That’s ridiculous,” Doug said.

As gas prices rise and carbon-footprint guilt becomes mainstream, this is likely a conversation taking place in more homes.

“Thinking about offshore drilling because we need to lessen our dependence on foreign oil and use our domestic oil—there’s something so wrong with that,” says Janet, an outreach coordinator for REI whose work is 4 1/2 miles away. “We need to lessen our dependence on oil in general.”

Forty percent of new Zipcar members cite fuel cost as a reason for joining, according to Portland Zipcar spokesman Nick Sowards. He also points out that Zipcar is averaging 10,000 new members per month in its locations in 26 states and provinces as well as London, England. That’s triple the number of new members joining at this time last year.

“I think we could do it,” says Sarah of a carless future. “I don’t see why we need a car.”

The plan for the family post-vehicle is to use Zipcar once a month to make big shopping trips and then bike, walk and use mass transit everywhere else. Once the girls return next month to their schools, both within a mile of home, the couple plans on biking their commute.

There are times, though, when a car is the only answer. The Hamiltons already used their $100 Zipcar credit to rent a minivan for a camping trip at Milo McIver State Park—a 56-mile round trip. The Hamiltons have realized they’ll have to tighten the radius of their activities.

Sarah is enrolled in a summer camp in Tryon Creek State Natural Area, a 20-mile round trip twice each day that the Hamiltons ride-share with friends.

“The most rewarding experience of the week has been the commute and bus time as quality time with the girls,” Janet says.

“The conversations have been rambling, meaningful, silly and wonderful. We all come home in a much better mood and because I have been forced to slow down, I don’t come home in a flurry with a list of things to do,” Janet says. “Slowing down has been a gift to us.”