The IRS released guidance explaining why the standard mileage rate for medical expenses is lower than the rate for business expense deductions. For 2010, the standard mileage rate for medical expenses is 16.5 cents per mile, while the rate for business expenses is 50 cents per mile.  The mileage rates differ because automobile expenses that are deductible medical expenses under Code Section 213 are not the same as those that are deductible business expenses under Code Section 162.