Increases in Fuel Economy to Reduce the Cost of Gas

Mpg for various countries into the future, from the UN DESA, 2011, shown by Kelly Rigg, Huffington post.

This graph shows that the European Union and Japan are already over 45 mpg average for new cars, and over 40 for the cars on the road.  The 2020 goal for the EU is 65 mpg, and for Japan is 55 mpg.  China is at about 38 mpg and its 2020 goal is 50 mpg.  California is already at 30 mpg.  The US was at 29.2 mpg for 2010 new vehicles.  The US 2025 requirement of 54.5 mpg for cars includes a lot of exceptions to continue making large SUVs and small trucks, only with more fuel efficiency than at present, such as hybrids.  The actual US average in 2025 will be about 43 mpg for new cars.  But since it takes about 15 years to replace the whole fleet, the average of cars on the road will take much longer to reach 43 mpg.  The US goal for 2016 is 35 mpg average, which will cut CO2 by 30%.  It will add about $1,000 to the cost of a new car, but save $3,000 in gas over its lifetime.  The US goal for heavy trucks is 20% better mpg by 2018.

New California rules are for a 75% reduction in nitrous oxides and other smog forming emissions by 2025, and for 1/7 of new vehicles to be zero emissions by 2025.

Electric cars are expensive, and plug in hybrids have short but very useful ranges on electricity such as 35 miles.  The government subsidies will not last long.  In an article on my website, I showed that the effective mpg of electric driving in terms of CO2 pollution, is 60 mpg for the national average, but is 105 mpg for cleaner SC Edison energy.  Again, two people carpooling in a Prius will be equivalent to 100 mpg each, without each spending an extra $40,000 for an electric car.

Lets add some relevant data condensed from the Transportation Energy Data Book of the Department of Energy on sales and mpg of components of the US vehicle fleet for 2010 (Chapter 4, Table 10).  Small car sales were 24% averaging 34 mpg, medium car sales were 22% averaging 33 mpg, large car sales were 19% averaging 28 mpg, SUV sales were 25% averaging 23 mpg, and pickup truck sales were 13% averaging 21 mpg.  Unfortunately, from Table 4.5 we see that US new car sales have fallen an average of 4.3% a year over the 2000-2010 decade.  The import percentage is about 33%.

For the effects of speed on driving, Table 4.26 of the Data Book shows the last tests in 1997 for nine vehicles that fuel economy loss from 55 mph to 65 mph was 9.7%, from 65 mph to 70 mph was an additional 8.2%, and over the whole range 55 mph to 70 mph was 17.1%.  From 70 to 75 the drop is an additional 7.5%.  From the speed limit of 65 to 75, a more typical California freeway result, the drop is 15%.  From Table 4.25 for hybrid vehicles, the dropoff from 65 to 75 mph was:  for a 2004 Prius, 26.3 percent; for a 2000 Insight 24.3%; for a 2007 Camry 14.5%; and for a 2008 Tahoe 11.1%.

 

About Dennis SILVERMAN

I am a retired Professor of Physics and Astronomy at U C Irvine. For two decades I have been active in learning about energy and the environment, and in reporting on those topics for a decade. For the last four years I have added science policy. Lately, I have been reporting on the Covid-19 pandemic of our times.
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