# Does the Prius have lower CO2 emissions than the Tessla Roadster?

“The only way to make an apples to apples comparison is to compare grams of CO2 emitted per mile traveled. Andrew has given us the figure 0.321 kwh per mile. The average emissions in the US to generate electricity is 1.4 pounds of CO2 per kwh based on the mix of generation sources. Therefore the Tesla emits 0.321 x 1,4 x 454 or 204 grams of CO2 for each mile travelled. Let’s go back to the lowly Escort that gets 30 mpg. A gallon of gasoline has a mass of 6.3 lbs. Gasoline has 2 hydrogen atoms for each carbon so gasoline is 12/14 carbon or a gallon of gasoline has 5.4 pounds of carbon. Carbon dioxide is 44/12 as heavy as gasoline so a gallon of gasoline equals 5.4 x 44/12 pounds of carbon dioxide or 19.8 pounds. The Escort has CO2 emissions of 19.8/30 x 454 grams per mile or 299.6 grams of CO2 per mile. The Tesla has 32% lower carbon foot print than an Escort. Now let’s compare the Tesla to a Prius that gets 50 MPG. The Prius has CO2 emissions of 179.8 grams per mile or 12% lower than o