No, not the metabolic CO2 emissions. It takes more CO2 to farm food, ship food, store food, make water, have heating, etc etc etc.... than driving a car.

I remember some random biology book saying how cars are 70% efficient, which is "much more" than the human body. Obviously that is wrong, but a car IS more efficient than a human in getting from point A to B. There was this experiment I did in which you had to pedal a bike to light a flashlight, which a simple AA can do a LOT better. But w/e.

It was a JOKE.... I think it is great to ride a bike, because if you read closely, I said that the energy is spent on you anyway, it just gets converted into fat. (So less fat AND save the environment)