~$10 a day taking into consideration that when I ride I go out to eat more, I spend money on light rail passes, and I buy bike crap which eats up some money. I still have my car, and maintinance on that thing is basically nil so it comes down to gas saved and food eaten. Car insurance is a non-issue. I pay only $40 less every 6 months becaue I dropped my mileage from 12k a year to 6k.