This SNAPSHOT is the first in a series of four focusing on the economics of conservaton. Data from the Wisconsin Department of Transportation and the U.S. Energy Information Administration was used to sevelo this article. The only data you will need to develop similar esitmates for your county is the number of automobiles registered in your county.

step 1: obaining the data from the Energy Information Administration Table 1.9 of the EIA's April 2007 Monthly Energy Review provides most of the data used in this article.

Simply go to the 2005 data (the last row of Table 1.9) to obtain the following:

2) Average fuel consmption per passenger vehicle was 541 gallons

3) Average mileage was 22.9 per passenger vehicle

step 2: obtaining the WiDOT County level data on the number of vehicles registered for Wisconsin is available in the WiDOT's Facts and Figures 2007 .

NOTE: The only "new number you will need to duplicate these estimates for any county in the U.S. is the number of autos registered in the county. In Dane County there were 213,198 automobiles registered in 2005.

the methodology:

• Estimate the total miles driven in 2005 by registered autos in Dane County by multiplying the number of registered autos in Dane County by the annual national average miles driven per registered auto in the U.S.

213,198 autos x 12,375 miles driven = 2,638,325,250 total miles driven

• Estimate the total gallons of gasoline used in 2005 by vehicles registered in Dane County by dividing total miles driven by the national average miles per gallon.

2,638,325,250 miles driven ÷ 22.9 mpg = 115,210,710 gallons

• Estimate the gallons that would be used if average mileage increased to 25 mpg by dividing total miles driven by 25 miles per gallon.

2,638,325,250 miles ÷ 25.0 mpg = 105,533,010 gallons used at 25 mpg

• Potential gallons saved by increasing average mpg to 25 mpg is calculated by simply subtracting gallons used at 25 mpg from gallons used at 22.9 mpg

115,210,710 - 105,533,010 = 9,677,700 potential gallons saved

 

• Gasoline saved to fuel almost 18,000 cars per year is calculated by dividing potential gallons saved by gallons consumed per vehicle per year

9,677,010 gallons saved ÷ 541 gallons per auto = 17,887 autos for one year

 

• per year is calculated as follows:

9,677,700 gallons saved x $3.00 per gallon = $29,033,100 saved per year

• To estimate that Dane County would save enough gasoline to fuel 9,000 cars per year was calculated as follows:

10 miles per week x 52 weeks = 520 miles saved per year per vehicle

213,198 registered autos x 520 miles per year = 110,862,960 total miles per year saved

10,862,960 total miles saved ÷ 22.9 mpg = 4,841,177 gallons of gasoline saved per year

4,841,177 gallons ÷ 540 gallons per auto = gasoline to fuel 8,965 autos for one year

17,887 + 8,965 ≈ 27,000 autos for one year