Deductions & credits

Portion of vehicle interest used for business is indeed a deduction you can claim in addition to the mileage rate. I just checked IRS guidelines again, Turbotax's guidelines, H&R Block's guidelines, and they all verify that. I've taken that deduction every year since I've had a car loan. I have since entered more precise information for my mileage (I made some corrections and vastly underestimated how many personal miles I drove), and it calculated my vehicle interest deduction at $303 (which would be correct - $913.90*(9036/27235)), and an additional $1149 for the mileage deduction - which obviously doesn't correspond to either 9036*57.5 cents or the other possibility I thought of - incorrect calculation of the mileage rate times the amount used for business. That also does not match up to what works out to 12.7 cents per each of 9036 miles. Clearly there is a bug.