California Environmental Protection Agency
Air Resources Board


MEMORANDUM

TO:              Peter D. Venturini, Chief Stationary Source Division

FROM:        Dean C. Simeroth, Chief Criteria Pollutants Branch

DATE:        October 8, 1996

SUBJECT:  IMPACT OF CLEANER-BURNING GASOLINE ON FUEL ECONOMY

Summary

To further evaluate the fuel economy impact of cleaner-burning gasoline, staff have reviewed both the Board of Equalization gasoline sales data and Caltrans traffic data. The data indicates that gasoline sales in 1996 for March through July are up 2.6 percent compared to the same period in 1995. Also, Caltrans data indicate that vehicle miles travelled have increased about 2 percent (plus or minus 1 percent) for March through July 1996 compared to the same period in 1995.

These data provide further confirmation that the impact of cleaner-burning gasoline on fuel economy is, as expected, in the range of a 1 to 3 percent decrease. Because we have used a five-month average that reduces variations in monthly reporting and are tracking both gasoline sales and traffic at the highest possible level of aggregation, staff has a high level of confidence in this conclusion.

Analysis

Based on Board of Equalization records for the five-month period of March through July 1996, average daily California gasoline consumption was 898,000 barrels per day. This represents a 2.6 percent increase over the same five months of 1995. See Table 1.

Caltrans traffic data for 17 trend count sites indicate a 2.0 percent increase in average daily traffic for March through July 1996 versus March through July 1995. See Table 2. This means that the vehicle miles traveled was up by about 2 percent in 1996 versus 1995 for those five months. Caltrans historical data indicates that the percent increase based on data from trend count sites is within 1 percent of the statewide increase in vehicle miles traveled. The average statewide increase in vehicle miles traveled for the last six traffic years has been 1.4 percent per year.

Compared to conventional and Federal reformulated gasoline sold in 1995, the statewide average energy content of California reformulated gasoline sold in 1996 was expected to be between 1 and 2 percent lower than the fuel in use in 1995. Therefore, we would expect about a 1 to 2 percent increase in statewide average fuel use associated with the advent of California's cleaner-burning gasoline program.

California gasoline consumption appears to be consistent with vehicle miles traveled and average fuel economy, as expected.

Table 1
Average Daily Gasoline Consumption
(bbl/day)

Month

1995

1996

Increase
March

858,520

897,840

4.6%

April

848,000

897,500

5.8%

May

871,740

885,650

1.6%

June

902,000

899,800

-0.2%

July

892,160

907,130

1.7%

Average 874,480 897,570

2.6%

Table 2.
Caltrans Trend Count Sites 1
Average Daily Traffic

Month

1995

1996

Increase
March

829,840

850,496

2.5%

April

982,541

1,005,919

2.4%

May

894,913

914,969

2.2%

June

971,556

990,838

2.0%

July

996,906

1,007,895

1.1%

Average

934,604

953,444

2.0%

1) 14 to 17; data not available from every site, every month