Originally Posted by
noglider
I'm not saying you should divide by time rather than miles. I'm saying that the result (cost per mile) is a function of the time at which you do the measurement. To me, that seems useless. Furthermore, you are taking the measurement at different times for the car and the bike. That's why the car comes out ahead. If you did analogous measurements, your comparison would be entirely different.
The car doesn't come out ahead. It still costs more per mile than the bikes do. And speaking of cost being a function of times of measurment, things are in favor of the bikes, since I bought them in August and October of last year, while the car was bought this year. If you'd like to argue that I drive much more than I ride, that's perfectly reasonable. However, arguing that I should divide the costs by months of ownership doesn't take into account whether a vehicle is actually used or not, which I find senseless.
Anyway, now I've really got to go. Catch you all later this evening!