What Kind of Fuel Economy Are Other Drivers Getting?

What Kind of Fuel Economy Are Other Drivers Getting?

 

Gas prices topping $3 a gallon have stirred consumers' interest in fuel
economy more than any time in the past 20 years, and have lead to record
numbers of visitors at www.fueleconomy.gov <http://www.fueleconomy.gov/>
.  Many would like to shop for a more fuel-efficient car or truck, but
are just not sure they can trust the government's MPG ratings.  In fact,
mounting criticism of the EPA's fuel economy numbers prompted the agency
to promise newer, more accurate MPG estimates starting in 2008.

 

Unfortunately, it's the 2007 model year that begins this month.  So
where can car buyers go right now to find real-world fuel economy
estimates?  The answer, of course, is the internet.  For more than a
year, drivers from all over the U.S. have been using the internet to
tell the government what gas mileage they get.  Now real-world fuel
economy ratings for more than 4,000 makes and models are available on
line at www.fueleconomy.gov <http://www.fueleconomy.gov/>  (see figure 1
below).  Neither the Department of Energy nor the EPA can vouch for the
accuracy or reliability of these real world estimates, although
precautions are taken to discourage bogus entries in the database.
You'll have to decide for yourself how useful the real-world ratings
are.

 

 

Figure 1.  Number of Real-World MPG Estimates by Model Year

 

 

If you use www.fueleconomy.gov <http://www.fueleconomy.gov/> 's "Find
and Compare Cars" or "Compare Side-by-Side" features, you'll see the
mileage drivers like you are getting in addition to the traditional EPA
ratings.  For example, 60 owners of the 2006 Prius have reported fuel
economy estimates ranging from 37 to 59 miles per gallon.  The average,
47.4 MPG, is considerably below the EPA rating of 55, but still
impressive gas mileage.  Likewise, 59 model year 2006 Honda Civic Hybrid
owners reported MPG numbers between 36 and 62.  They averaged 46.5 MPG,
a little closer to the Civic Hybrid's EPA rating of 50.  Fourteen
Pontiac Solstice owners reported MPG estimates averaging 24.6 miles per
gallon, a little better than the EPA's rating of 23 MPG for the vehicle.

 

 

 

 

 

Analyzing the real-world MPG data, researchers at the Department of
Energy's Oak Ridge National Laboratory have found that the EPA ratings
do a decent job of predicting the average fuel economy of all drivers of
a given make and model.  The 4,000+ real-world MPG ratings are fairly
evenly scattered about a line representing real-world MPG equals EPA
combined city-highway MPG (see figure 2 below).  The problem is that
mileage varies so much from one driver to another and one place to
another that the government ratings are a poor predictor of what any
individual driver is likely to get with his or her vehicle.  If the EPA
rates a car at 20 MPG, the real-world data show that you might do as
well as 30 MPG or as poorly as 10 MPG.  The researchers believe that
it's the inability to accurately predict any given drivers fuel economy
that gives the government ratings their poor reputation.

 

 

 

Figure 2.  Real-World and EPA Fuel Economy Estimates

 

 

For years, www.fueleconomy.gov <http://www.fueleconomy.gov/>  has been
the single most comprehensive source of information related to fuel
economy, featuring MPG data for all cars and light trucks sold in the
United States since 1985, up-to-date information on finding the cheapest
gas, and driving and maintenance tips for maximizing fuel economy. With
the addition real-world MPG data, the web site is even more
comprehensive and useful than ever.

 

If you have any comments or questions, please e-mail or call me
(865-574-4694).

 

Bo Saulsbury

National Transportation Research Center

Oak Ridge National Laboratory