The IRS announced an increased mileage rate for the last half of 2011 due to high fuel costs.
Starting 7-1-11, the optional rate for business use of vehicles is 55.5 cents per mile. For medical and moving the optional rate is 23.5 cents per mile.
Most ministries and businesses use the IRS rate for reimbursing staff for personal use of their vehicles. An amount up to that level is considered to be ‘substantiated’.
The official source is Announcement 2011-40.
Previous rates of 51 cents and 19 cents were mentioned here.