New fuel efficiency law begins with lies

At the end of November, 2007, the United States has been treated to a Congressional love-in. Supposedly there was unity, at least among Democrats, around a new law to improve fuel efficiency of motor vehicles. Here is a typical description, taken from a December 1, 2007, Associated Press story: "Automakers would be required to meet an industry-wide average of 35 miles per gallon for cars and light trucks, including sport utility vehicles, by 2020...." What does that really mean?

Earlier in the year many newspapers ran stories about revised government standards for measuring fuel efficiency, producing lower ratings for miles per gallon than before in the interest of truthful reporting. For example, Warren Brown wrote in the October 21, 2007, Washington Post, "Federal gas mileage estimates for 2008-model cars and trucks will be 12 to 30 percent lower than those for 2007 models."

Stories about a proposed new fuel efficiency law did not say how "35 miles per gallon" was to be measured. It makes a difference. Measured using current standards, the U.S. Environmental Protection Agency (EPA) estimates average efficiency for all automobiles and light trucks combined, sold in the U.S. during 2006, was 20.1 miles per gallon [1]. Improving from 20.1 to 35.0 miles per gallon would mean a 74 percent increase in efficiency.

However, under former measurement standards the average efficiency for all automobiles and light trucks combined, sold in the U.S. during 2006, was 25.3 miles per gallon [2]. Improving from 25.3 to 35.0 miles per gallon would mean only a 38 percent increase in efficiency. Since some news stories about the proposed new law have spoken of a "40 percent" improvement, it is clear that an obsolete and dishonest approach to rating fuel efficiency is being revived for the benefit of a new law.

From 1975 to 1981, following enactment of the original fuel efficiency law, manufacturers increased average efficiency from 13.1 to 20.5 miles per gallon, as estimated by EPA [3] using current measurement standards. That represented a 56 percent improvement achieved in six years. Since 1981 there has been no more sustained improvement. Average fuel efficiency for 2006 was less than the level achieved 25 years before. What happened?

As a 2006 EPA report [4] shows, major gains in fuel efficiency from 1975 through 1981 came from reducing average vehicle weight, falling from about 4050 to 3200 pounds. After 1981 manufacturers continued to improve potential fuel efficiency, but instead of making that efficiency available to reduce fuel use, on average they used it to boost vehicle weight and performance. From 1981 to 2005 average weight grew from about 3200 to 4100 pounds, and average time of accelerate to 60 miles per hour shrank from about 14.4 to 9.8 seconds.

Fuel use tends to track vehicle weight. The drop in average weight from 1975 to 1981 was enough to provide about 27 percent improvement in fuel efficiency, near half what was achieved during those years. If the subsequent regrowth in vehicle weight from 1981 to 2005 were to be reversed, that factor alone would provide most of the 38 percent improvement that the proposed new law would apparently require, leaving only about a 10 percent improvement needed from technology over a dozen years.

The 1975 Energy Policy and Conservation Act (Public Law 94-163) sought a bold rate of progress. Within 10 years average fuel efficiencies for cars and for light trucks were to reach 27.5 and 20.7 miles per gallon. At the time, light trucks represented about 20 percent of light vehicle sales, so a combined efficiency of 26.1 miles per gallon could be expected, doubling the average efficiency now estimated by EPA for 1975. The goal was equivalent to a cumulative improvement of 7.2 percent per year.

Fuel efficiency goals of the 1975 law were subverted by two major means. Although it was soon recognized that government efficiency ratings were almost always higher than practical experiences, political pressure joined with bureaucratic inertia to freeze the system, and the measurement standards did not change for over 30 years. By 1985 manufacturers had also begun to promote light trucks used as though they were cars, relaxing efficiency requirements and increasing profits. Average efficiency peaked in 1987, well short of goals, and has since dropped below the 1981 level.

The proposed new fuel efficiency law is a timid step toward renewed progress. It is equivalent to a cumulative efficiency improvement of 2.8 percent per year. However, if manufacturers were again to reduce vehicle weight as they did before, down to 1981 levels, then only 0.8 percent per year improvement would be needed from technology.

Progress in 1975 was achieved after the threat of the 1973 Arab oil embargo, triggering the worst economic crash since the Great Depression, and during the term of the country's only unelected President, who had pardoned crimes of his predecessor but still hoped to win a term of his own. Today's threats are global warming and worldwide demands for oil, raising the price of gasoline. Is that enough?

A more responsible approach than the recently reported proposal could aim for 35 miles per gallon using the current standards for measuring fuel efficiency. That would be equivalent to a cumulative improvement of 4.7 percent per year, less than the cumulative 7.7 percent per year rate achieved between 1975 and 1981 but sustained for twice as long a period. Some improvement can again be won by shrinking vehicle weight, but a substantial part must also come from technology.

---

[1] U.S. Environmental Protection Agency, Light-Duty Automotive Technology and Fuel Economy Trends: 1975 through 2007, Appendix A, Table A-2, Light-Duty Vehicle Adjusted Fuel Economy, Cars and [Light] Trucks, Composite 3-year Moving Average, 2006, available at www.epa.gov/otaq/cert/mpg/fetrends/420r07008a.pdf.

[2] U.S. Environmental Protection Agency, Light-Duty Automotive Technology and Fuel Economy Trends: 1975 through 2007, Appendix A, Table A-1, Comparison of Laboratory 55/45 MPG, Both [Cars and Light Trucks], Revised Estimate, 2006, available at www.epa.gov/otaq/cert/mpg/fetrends/420r07008a.pdf.

[3] Robert M. Heavenrich, Light-Duty Automotive Technology and Fuel Economy Trends: 1975 Through 2006, U.S. Environmental Protection Agency Report EPA420-R-06-011, July, 2006, Table 1, Cars and [Light] Trucks, Adjusted 55/45 MPG, 1975 through 1981, available at www.epa.gov/oms/cert/mpg/fetrends/420r06011.pdf.

[4] Robert M. Heavenrich, Light-Duty Automotive Technology and Fuel Economy Trends: 1975 Through 2006, U.S. Environmental Protection Agency Report EPA420-R-06-011, July, 2006, Weight and Performance (chart, p. v), available at www.epa.gov/oms/cert/mpg/fetrends/420r06011.pdf.