According to the Save the Planet website, six 25-year old pine trees can absorb 1 ton of CO2.
About 20 years ago, we planted about 1,000 pine trees on my parents' property:
This means that (when they are 25) they will absorb 166 tons of CO2 annually. My sedan accounts for about 4.6 tons and our SUV accounts for about 6.6 tons. So at 6 tons average per vehicle (depending on mileage, of course), the 1,000 trees we planted are more than covering the carbon footprint for all vehicles in my family. Actually, this covers about 27 vehicles per year until the trees are gone!
I just feel really good about myself knowing that I'm "green" as far as my vehicles go.... Hopefully you can see the humor in this - if not, then go out and find 6 pine trees to call your own so that you can live green too. That's a whole lot cheaper than buying a "green" car and it's officially sanctioned by our former VP!
Speaking of "green", I saw a car the other week with one of the "Live Green" banners on the bumper. Was it a Prius? Nope. It was a 1995 Mustang GT - the little V8 must be green, eh? ;) Maybe the lady found some pine trees!