APTA then compares the average monthly transit fare to the average cost of driving. The cost of driving is calculated using the 2011 AAA average cost of driving formula. AAA cost of driving formula is based on variable costs and fixed costs. The variable costs include the cost of gas, maintenance and tires. The fixed costs include insurance, license registration, depreciation and finance charges. The comparison also uses the average mileage of a mid-size auto at 23.4 miles per gallon and the price for self-serve regular unleaded gasoline as recorded by AAA on February 21, 2012 at $3.57 per gallon. The analysis also assumes that a person will drive an average of 15,000 miles per year. The savings assume a person in two-person household lives with one less car.
In determining the cost of parking, APTA uses the data from the 2011 Colliers International Parking Rate Study for monthly unreserved parking rates for the United States.
To calculate your individual savings with or without car ownership, go to www.publictransportation.org.