what would 44mpg be?
CO2 isn't important.
It is not a pollutant and not the cause of "global warming".
100% fact. You don't have to believe everything the TV tells you. Learn a bit about science, look at the facts and you can see how extremely misleading the "global warming" alarmists have been.
CO2 is an 0.03% of the total atmosphere, far to little to affect much of anything. Walk into a movie theater and fart (or burp if you prefer), that is about how much total CO2 is in the air. 1,190,000,000 billion tonns of CO2 is theoretically added to the atmosphere each year. This isn't even a drop in the bucket compared to the atmosphere's 5 million billion tons (5.5 x 10,000,000,000,000,000,000kg).
There are three primary contributors to the global temperature: The sun, humidity in the air, and the oceans. CO2 rises with temperature because the oceans absorb heat and evaporates quicker to release gases contained within.
Just like Global Cooling, the Millennium Bug, Africanized Killer Bees, Fire Ants, The Plague II, West Nile Virus, Killer Asteroids, SARS, and Bird Flu. It will eventually prove itself wrong and/or significantly over hyped and something else will be invented that will supposedly spell doom for all humanity.
In the mean time, worry about the important things in a car such as fuel economy, reliability and upkeep.