@Andy Bondhus, I would direct him to §4.03 of Rev. Proc. 2010-51. Interest on an automobile purchase (to the extent of business use of course) is included along with parking fees, tolls, and taxes as a "separate item" distinguished from the "fixed and variable costs" described in §4.02 that are not deductible when using the standard mileage rate.
The theory here is that the "standard mileage rate" is the sum of "fixed and variable costs" such as depreciation or lease payments, maintenance and repairs, tires, gas, oil, insurance, license/registration fees, etc., on a per-mile basis.
However, this "standard mileage rate" does not (theoretically, of course) include the "separate items" of parking fees, tolls, interest, and taxes, and so these may be deducted in addition to taking the standard mileage rate.
Also, I assume your car is relatively old or inexpensive such that the standard mileage method makes sense as opposed to the actual expense method?
@Christopher Phillips is correct that generally one may not deduct "actual" expenses when using the standard mileage method, but there are certain exceptions to the rule as described above.
