It’s been seven months since I put a full tank of gas in my car. I haven’t stopped driving; I’m just on the pay-as-you-go plan.

Lucky for me, I take public transportation to my day job – and I use it a lot to get around on weekends, too. But I’m somewhat atypical. Life in America, particularly when kids are in tow, is near-impossible to manage without a car.

Who I choose to visit is becoming a conscious budgetary decision. As I buy by the gallon, shelling out $10 or $15 a pop depending on the length of the trip, I’m reminded of that classic Seinfeld episode in which Elaine contemplates which of her boyfriends is “sponge-worthy.” But I digress.

I’m old enough to remember the era of pre-dawn gas lines and rationing fuel purchases based on whether the last digit of your license plate was even or odd. Things haven’t gotten quite that extreme. Yet.

As I struggle to parallel park behind yet another unwieldy, oversized SUV on my urban street, it makes me wonder what became of the impetus to rein in energy consumption. Tell me: Who needs a Hummer (GM) in Hoboken?

We weekend soccer moms (and dads) are doing a lot more carpooling to the away games these days. I think thrice about jumping in the car and just taking a joy ride. I shop locally, use email, IM and Facebook for my further-flung friends and walk more than ever. If we had more bike racks, I’d even consider that.

Last summer I revisited Copenhagen, where I lived and studied as a junior in college. A biking city even decades ago, things have gotten even more progressive. All the major commercial arteries and highways have designated bike lanes set off from vehicular traffic by wide grassy knolls and dividers. The bike lanes are the ones with the traffic jams.

But it gets better.

Throughout the city there are public bike stands where, for a token deposit of about $3, you can pick up a bike. Once you reach your destination, you just drop off the bike at another public stand and retrieve your deposit. It’s efficient, civilized and fun. It’s not just the diet that keeps the Danes so lithe.

For two years, the Parents’ Association at my daughter’s school tried to get a bike stand erected so that kids in our mile-square city could have the chance to ride a bike to school. It wasn’t the cost, but the bureaucratic red tape, that finally killed the proposal.

How have your driving habits changed? Weigh in on The Exchange.