Originally Posted by
noglider
So if we've discussed this in the past, I have not come to agree that vehicle costs are nonlinear. There are fixed costs, but they are smaller than the marginal costs.
Since you continue to reference the "Federal Allowance for driving" in a discussion of the $ savings/per mile of bike commuting, this IRS reference about the fixed and variable components of this IRS deduction "allowance" is provided FYI.
IRS mileage rates for 2025
Beginning Jan. 1, 2025, the standard mileage rates for the use of a car, van, pickup or panel truck will be:
70 cents per mile driven for business use, up 3 cents from 2024.
21 cents per mile driven for medical purposes, the same as in 2024.
21 cents per mile driven for moving purposes for qualified active-duty members of the Armed Forces, unchanged from last year.
14 cents per mile driven in service of charitable organizations, equal to the rate in 2024.
The rates apply to fully-electric and hybrid automobiles, as well as gasoline and diesel-powered vehicles.
While the mileage rate for charitable use is set by statute, the mileage rate for business use is based on an annual study of the fixed and variable costs of operating an automobile. The rate for medical and moving purposes, meanwhile, is based on only the variable costs from the annual study.