promises to... Go without a car

"Our only vehicle (a 23 year old VW Vanogan) died and my wife and I decided not replace it -- for at least one year starting October 18, 2007. During that year we will avoid releasing about 7 metric tons from going into the atmosphere, about 3 times the van's weight. (This includes credit for 1/12th the embodied energy from not manufacturing another vehicle. It subtracts polution created when we rent a car or when people go out their way to give us a ride.) We'd like to renew our commitment, but let's get throught the first year first."