I'm considering driving instead of flying, from S.F. to Dallas, and trying to see if there's a significant environmental difference. My rough calculations use the following data: (Airline CO2 calculator available here: http://www.climatecare.org/britishairways/index.cfm) .27 british tons of CO2 from S.F. to Dallas, or 274,332.66 grams each way, per passenger Distance shows to be 1716 miles if driven, or 2761 km, giving roughly 99 grams/km emissions per passenger (seems low!). For two people that's about 198 grams/km total. I think the Prius figures being published are 104 grams/km. Does that figure change appreciably with two people in the car? Is it accurate to begin with?
