The cost of driving is based on the distance driving between your start and end addresses, multiplied by the standard cost per mile that tax regulations allow businesses to deduct. However, this number is only an estimate and doesn't consider tolls, parking fees, or variations in gas mileage for different types of cars.
Cost of driving is currently available for US cities only. The cost of driving estimate is presented next to the cost of the transit trip for comparison purposes only. These calculations are based on an annual study of the fixed and variable costs of operating an automobile. Runzheimer International, an independent contractor, conducted the study for the IRS.