How are fuel economy estimates obtained?
Why is the fuel economy of my car different
from the estimates in the fuel economy guide?
What should I do if my fuel economy is excessively
low?
How are vehicle size classes defined?
What is the Gas Guzzler tax?
How are total annual greenhouse gases determined?
Where can I find more information about hybrid
vehicles?
What does gasoline cost?
Should I use Premium or Regular gasoline?
Where can I find more information about CAFE?
What tax incentives are available for alternative
fuel and hybrid vehicles?
Why don't you have ratings for large pickup trucks and SUVs?
Where does gasoline from my local station come from?
How
are fuel economy estimates obtained?
The fuel economy estimates are based on results of tests required
by the U.S. Environmental Protection Agency (EPA). These tests
are used to certify that vehicles meet the Federal emissions and
fuel economy standards. Manufacturers test pre-production prototypes
of the new vehicle models and submit the test results to EPA.
EPA re-tests about 10% of vehicle models to confirm manufacturer's
results. The vehicles are driven by a professional driver under
controlled laboratory conditions, on an instrument similar to
a treadmill. These procedures ensure that each vehicle is tested
under identical conditions; therefore, the results can be compared
with confidence.
There are two different fuel economy estimates for each vehicle
in the Fuel Economy Guide, one for city driving and one for highway
driving. To generate these two estimates, separate tests are used
to represent typical everyday driving in a city and in a rural
setting. Two kinds of engine starts are used: the cold start,
which is similar to starting a car in the morning after it has
been parked all night; and the hot start, similar to restarting
a vehicle after it has been warmed up, driven, and stopped for
a short time.
The test used to determine the city fuel economy estimate simulates
an 11-mile, stop-and-go trip with an average speed of 20 miles
per hour (mph). The trip takes 31 minutes and has 23 stops. About
18 percent of the time is spent idling, as in waiting at traffic
lights or in rush hour traffic. The maximum speed is 56 mph. The
engine is initially started after being parked overnight. Vehicles
are tested at 68 F to 86 F ambient temperature.
The test to determine the highway fuel economy estimate represents
a mixture of "non-city" driving. Segments corresponding to different
kinds of rural roads and interstate highways are included. The
test simulates a 10-mile trip and averages 48 mph. The maximum
speed is 60 mph. The test is run with the engine warmed up and
has little idling time and no stops (except at the end of the
test).
NOTE: To make the numbers
in the Fuel Economy Guide more useful for consumers, EPA adjusts
these laboratory test results to account for the difference between
controlled laboratory conditions and actual driving on the road.
The laboratory fuel economy results are adjusted downward to arrive
at the estimates in the Fuel Economy Guide and on the labels seen
on new cars, light trucks, and vans. The city estimate is lowered
by 10% and the highway estimate by 22% from the laboratory test
results. Experience has proven that these adjustments make the
mileage estimates in the Fuel Economy Guide correspond more closely
to the actual fuel economy realized by the average driver.
Additional Information on this topic is available at:
About the EPA Fuel Economy Ratings
Why
is the fuel economy of my car different from the estimates in
the fuel economy guide?
Top of page
Some consumers may notice that their fuel economy estimates
differ from EPA's estimates. This can be caused by any of several
factors related to driving conditions, driver behavior, vehicle
maintenance, and fuel characteristics as explained below.
It is impossible for laboratory tests to simulate all driving
conditions and driver behavior: EPA fuel economy estimates
are based on tests conducted by manufacturers on a limited number
of pre-production prototype vehicles. EPA then verifies these
tests on about 10-15 percent of each year's models. The tests,
which are the same for all vehicles, are designed to simulate
city and highway driving conditions. However, these tests cannot
simulate the conditions under which each vehicle is driven or
each person's driving style. Therefore, the following driving
conditions and behavior can affect your fuel economy:
How
are vehicle size classes defined? Top
of page
The size class for cars is determined by measuring the interior
volume as described below. The size class for trucks is defined
by the gross vehicle weight. Fuel economy regulations do not apply
to heavy-duty vehicles. These models do not have fuel economy
labels in the window and are not included in this Guide.
|
CARS |
| Two-Seaters |
Cars designed to seat primarily two adults |
| Sedans: |
|
| MInicompact |
Less than 85 cubic feet of passenger and luggage volume
|
| Subcompact |
Between 85 and 99 cubic feet of passenger and luggage volume |
| Compact |
Between 100 and 109 cubic feet of passenger and luggage
volume |
| Mid-Size |
Between 110 and 119 cubic feet of passenger and luggage
volume |
| Large |
120 or more cubic feet of passenger and luggage volume
|
|
STATION
WAGONS |
| Small |
Less than 130 cubic feet of passenger and cargo volume
|
| Mid-Size |
Between 130 and 159 cubic feet of passenger and cargo volume
|
| Large |
160 or more cubic feet of passenger and cargo volume |
|
TRUCKS |
| Small Pickup Trucks |
have a gross vehicle weight rating (truck weight plus carrying
capacity) under 4,500 pounds |
| Standard Pickup Trucks |
have a gross vehicle weight rating (truck weight plus carrying
capacity) of 4,500 to 8,500 pounds |
|
MINIVANS, SPORT
UTILITY VEHICLES, AND SPECIAL PURPOSE VEHICLES |
The passenger volume reported on this site is an estimate of
the size of the passenger compartment. The luggage volume is the
size of the trunk or, in station wagons and hatchbacks, the cargo
space behind the second seat. In a few cases, the addition of
passenger and cargo volume numbers indicate that a vehicle should
be in the next higher classification. This is not the case as
the data have been rounded to the nearest whole number.
The interior volume is measured using SAE Recommended Practice
J1100 as per EPA Fuel economy regulations, reg. 40 CFR 600.315-82
"Classes of Comparable Automobiles." Automobile manufacturers
calculate the interior volume of their vehicles and submit this
information to EPA.
The SAE procedure calculates interior volume from many height,
width and length dimensions inside the vehicle, including head
room, foot room, seat width, etc. The trunk volume is typically
determined by putting many suitcase sized boxes in the trunk and
adding up the volume of each box.
What
is the Gas Guzzler Tax?
Top of page
The Energy Tax Act of 1978 established a Gas Guzzler Tax on
the sale of new model year vehicles whose fuel economy fails to
meet certain statutory levels. The gas guzzler tax applies only
to cars (not trucks) and is collected by the IRS. The fuel economy
figures used to determine the Gas Guzzler Tax are different from
the fuel economy values provided on this web site and the Fuel
Economy Guide. The tax does not depend on your actual on-the-road
mpg, which may be more or less than the EPA published value. The
purpose of the Gas Guzzler Tax is to discourage the production
and purchase of fuel inefficient vehicles. The amount of any applicable
Gas Guzzler Tax paid by the manufacturer will be disclosed on
the automobile's fuel economy label (the window sticker on new
cars).
|
GAS GUZZLER
TAX |
|
Unadjusted
MPG(combined)* |
Tax |
| at least 22.5 |
No tax |
| at least 21.5, but less than 22.5 |
$1000 |
| at least 20.5, but less than 21.5 |
$1300 |
| at least 19.5, but less than 20.5 |
$1700 |
| at least 18.5, but less than 19.5 |
$2100 |
| at least 17.5, but less than 18.5 |
$2600 |
| at least 16.5, but less than 17.5 |
$3000 |
| at least 15.5, but less than 16.5 |
$3700 |
| at least 14.5, but less than 15.5 |
$4500 |
| at least 13.5, but less than 14.5 |
$5400 |
| at least 12.5, but less than 13.5 |
$6400 |
| less than 12.5 |
$7700 |
* The combined fuel economy MPG value (55 % city, 45 % highway)
is used to determine tax liability. The MPG value is also adjusted
slightly to account for differences in test procedures made since
the base year. The MPG value is not adjusted for in-use short
fall. The unadjusted combined MPG of a vehicle can be approximated
from the city and highway values provided in the Fuel Economy
Guide and on this website by the following equation:
(1/(.495/city
MPG + .351/highway MPG))+.15
Since this is an approximate calculation, the actual
gas guzzler tax may be off by one tax bracket.
How
are total annual greenhouse gas emissions estimated?
Top of page
The greenhouse gas estimates presented here are
full fuel-cycle estimates, combining the three major greenhouse
gases emitted by motor vehicles: carbon dioxide, nitrous oxide,
and methane. Full fuel-cycle estimates include all steps in the
use of a fuel, from production and refining to distribution and
final use. Because of this they give a more complete picture of
the impacts on global warming of use of a particular fuel.
Some gases have greater impacts on climate than
others. Scientists have developed relative global warming potential
numbers for each gas that gives its impact on global climate realtive
to that of carbon dioxide. We use the global warming potentials
developed by the Intergovernmental Panel on Climate Change to
combine the three gases into tons of carbon dioxide equivalent.
We believe this gives the most compete and accurate reflection
of the impact of each vehicle's energy use on the global climate.
Numerous assumptions and calculations are necessary
to estimate full fuel-cycle greenhouse gas emissions in carbon
dioxide equivalents. Because of this, estimates from different
sources will vary. Our estimates are taken from the U.S. Department
of Energy's GREET model, version 1.5 developed by Argonne National
Laboratory. Additional information is available at:
http://www.transportation.anl.gov/ttrdc/greet/
Where
can I find more information about hybrid vehicles?
Top of page
To
help consumers understand, "just what is a hybrid anyway?" DOE
created the Technology Snapshot series. The Snapshot brochures,
available electronically on www.fueleconomy.gov, describe a particular
vehicle technology and how it works, in plain English. Each one
also features a different commercially available vehicle and provides
an overview of its performance, fuel economy, and emissions. DOE
hopes the Snapshots will spark consumer interest in hybrid-electric
and other advanced technology vehicles, and plans to continue
the series as new models become commercially available.
Toyota
Prius Technology Snapshot
Honda Insight Technology
Snapshot
Honda Civic Hybrid Technology
Snapshot
What
does gasoline cost?
Top of page
Links to information on the cost of gasoline in
the United States can be found in fueleconomy.gov's Gasoline
Price Section
Should
I use regular or premium gasoline?
The answer is currently available at the FTC's web
site:
http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm
Where
can I find more information about CAFE?
Information on U.S. fuel economy regulations is
available at:
http://www.nhtsa.dot.gov/cars/rules/cafe/index.htm
http://www.epa.gov/otaq/mpg.htm
http://www.epa.gov/otaq/cert/factshts/fefact01.pdf
What
tax incentives are available for alternative fuel and hybrid vehicles?
Qualifying electric vehicles and clean-fuel vehicles (including
gasoline/electric hybrids) purchased new are eligible for federal
income tax incentives.
The current incentive is scheduled to phase out in 2004-06.
Important:
Congress is currently considering legislation that may alter the
tax incentives for hybrid vehicles. We will provide additional
information if any of these incentives change.
Some state and local governments also provide incentives for
alternative fuel vehicles, so you may want to check with your
state or local government. The U.S.
Department of Energy's Clean Cities Vehicle Buyer's Guide for
Consumers may also have useful information on state/local
incentives.
Why
don't you have ratings for large pickup Trucks and SUVs
Vans, pickup trucks, and sport utility vehicles (SUVs) weighing
more than 8,500 pounds gross vehicle weight are classified as
heavy-duty vehicle. Fuel economy regulations do not apply to these
vehicles, so they are not tested and fuel economy labels are not
posted in their windows.
