Accounting honestly for vehicle usage
The IRS allows $0.585 per mile for business use of a vehicle, plus actual parking fees (but not parking fines) and tolls. Since they are not generally known for their generosity, I suspect that this figure is a fair representation of the actual cost of operating the average vehicle. My vehicle, a 2004 Toyota Avalon XLS which gets around 20mpg in mixed city/highway driving, is probably about average. Accounting only for fuel and failing to account for the true cost of driving is the reason so many people perceive public transit as being more expensive than driving. I am, fortunately, smarter than that and take public transit whenever practicable, which admittedly isn't often as I'm often starved for time, and unless you're going into San Francisco at rush hour, public transit generally takes longer than driving.
Starting January 1, 2010, I am going to take weekly odometer readings and start putting $0.585 in cash per mile actually driven into a Pringle's can or similar container. When the IRS changes the rate, I'll change what I put in the can. Whenever I buy fuel or need repairs, oil changes, tires, scheduled maintenance, insurance, registration, smog inspection, or anything related to my car except parking fees, parking fines, or tolls, I will take the money out of the Pringle's can. Every three months, I will deposit the contents of the can into an interest-bearing savings account or, ideally, a certificate of deposit or treasury bill maturing in January 2019. When my car is no longer economically feasible to drive (I'm predicting another 140,000 miles [it has 60,000 now] or 9-10 years from now), I will take any money in the can/account and put it towards purchasing another car, assuming we haven't come up with an entirely different way to travel by then. I suspect there won't be much money left.
What do you think?