My wife put it best the other day.
Her bike gets 15 mpg better than the car. But if she rides the bike into work. She'll ride at least 30 miles more a day.
But the Smiles per gallon, now there is no comparison.
Oh and she's one smart cookie. The daycare we use is on MY way to work. So I have to take Charlotte, so no bike for me unless I come home and switch.