If you're doing a comparative analysis of your transportation options, bicycle seems to just keep getting better.
The American Automobile Association - hardly an anti-car group! - just released their annual "Driving Cost" study. Not surprisingly, costs are up. According to them, it costs 58.5 cents/mile to own and operate an average sedan ($8776/year - that's based on 15,000 annual miles). SUV drivers pay a premium for such prestige - 74.9 cents/mile ($11,239 annually).
Costs included: insurance, license/registration, taxes, depreciation, finance charges, fuel, maintenance, and tires.
Depreciation alone costs $3,728/year. Ouch! So just having a car sitting in a driveway or garage will cost you ten bucks a day. (Fortunately in real life, depreciation trails off. So if you have an old beater that you use now and then, your cost will likely vary considerably.)
The AAA started releasing the annual study in 1950. That year, it cost 9 cents/mile to own a car. (And yearly numbers were calculated on 10,000 miles/year, rather than 15,000.)
Personally, I'm glad I ride a bike, because I don't have $8800 per year of "slush" in my budget! Ding-ding-ding-ding...