Every mile you ride a bike instead of driving a car is a mile that you don't have to pay for gas to travel. It's that simple. Doesn't work for everyone because some places are actually hostile to cyclists and are built exclusively for cars. But I used to ride a scooter on the highway 10 miles to get to work of the 5 times I've been hit by something, only one of them was on the dangerous part of the commute.
Still kicking ass carfree and laughing at the people who spend half their paychecks on gas and car payments and insurance and mechanic bills and toll bills and you get the idea.