Emission Facts

Average Annual Emissions and Fuel 

Consumption for Gasoline-Fueled 

Passenger Cars and Light Trucks The amount of pollution that a vehicle emits and the rate at which 

it consumes fuel are dependent on many factors. The U.S. 

Environmental Protection Agency (EPA) has developed a series of 

computer models that estimate the average emissions for different 

types of highway vehicles. This fact sheet is one of a series on high-

way vehicle emission factors. It presents average annual emissions and 

fuel consumption for gasoline-fueled light-duty vehicles (passenger 

cars) and light-duty trucks (pickup trucks, sport-utility vehicles, and 

the like).

Introduction

There are a number of factors that affect the rate at which any vehicle emits air 

pollutants. Some of the most important are: • vehicle type/size (passenger cars, light-duty trucks, heavy-duty trucks, urban and 

school buses, motorcycles)

• vehicle age and accumulated mileage • fuel used (gasoline, diesel, others) • ambient weather conditions (temperature, precipitation, wind) • maintenance condition of the vehicle (well maintained, in need of maintenance, 

presence and condition of pollution control equipment)

• how the vehicle is driven (e.g., long cruising at highway speeds, stop-and-go 

urban congestion, typical urban mixed driving)

Office of Transportation and Air Quality

EPA420-F-08-024

October 2008
Emission Facts

The most current version of the computer model that EPA uses to estimate average in-use emissions 

from highway vehicles is MOBILE6.2. EPA, the States, and others use this model to estimate 

total emissions of pollutants generated by highway vehicles in various geographic areas and over 

specific time periods. The emission rates or “emission factors” presented in this fact sheet are

based on national average data

representing the in-use fleet as of 

July 2008. 

The emission rates for hydrocarbons (both volatile organic 

compounds [VOCs] and total 

hydrocarbons [THC]), carbon 

monoxide (CO), nitrogen oxides 

(NOx), and particulate matter 

(PM10 and PM2.5) are presented in 

the following tables. The hydrocarbon (HC) numbers include 

both tailpipe and evaporative 

emissions, whereas the rates for 

the other pollutants are for tailpipe emissions only. 

The emission rates assume an average, properly maintained vehicle, operating on typical gasoline 

on a warm summer day. Emission 

rates can be higher in very hot 

weather (especially HC) or very 

cold weather (especially CO).

National average values are used 

for registration distributions by 

age (what fraction of all vehicles 

of each specific type, in use today, 

are of the current model year, 

one to two years old, two to three 

years old, and so forth up to 25 

years old) and annual mileage 

accumulation rates by age (newer 

vehicles tend to be driven more 

miles per year than do older vehicles). Some of the other primary 

assumptions incorporated in these 

emission factors are:

Abbreviations and Acronyms Used

CO: Carbon monoxide; a regulated pollutant

CO2: Carbon dioxide; the primary byproduct of 

 all fossil fuel combustion

FTP: Federal Test Procedure; the primary test 

 used in certifying vehicle compliance with 

 emission standards

g: gram(s)

g/mi: grams per mile

GHG: Greenhouse gas or gases, such as CO2, 

 that accumulate in the atmosphere and

 contributes to potential climate change

HC: Hydrocarbons; molecules formed of hydrogen 

 and carbon that constitute gasoline, diesel, 

 and other petroleum-based fuels; a 

 regulated pollutant

lb: pound

NOx: Nitrogen oxides; a regulated pollutant

PM10: Particulate matter under 10 microns 

 diameter; a regulated pollutant

PM2.5: Particulate matter under 2.5 microns 

 diameter, sometimes referred to as 

 “fine particulate”

ppm: parts per million

psi: pounds per square inch

RVP: Reid vapor pressure; a standardized meth

 od for expressing the volatility, or tenden

 cy to evaporate, of gasoline

SUV: Sport-utility vehicle; a subset of all light-

 duty trucks; examples include most Daim

 ler-Chrysler Jeep models, Ford Escape, 

 Ford Explorer, GMC Yukon, etc.

THC: Total hydrocarbons

VMT: Vehicle miles traveled

VOC: Volatile organic compounds; equivalent 

 to THC plus aldehydes minus both 

 methane and ethane
Emission Facts



•	 Ambient temperature: 72 to 92 °F day time range

•	 Nominal gasoline volatility: 9.0 psi RVP

•	 Weathered fuel volatility: 8.6 psi RVP

•	 Gasoline sulfur content: 30 ppm

•	 Average speed: 27.6 miles per hour

•	 I/M program: No

•	 Reformulated gasoline: No

These calculations are based on average annual passenger car mileage of 12,000 miles and average annual light-duty truck mileage of 15,000 miles. Fuel consumption is based on the estimated 

average in-use fuel economy: 24.1 miles per gallon (mpg) for passenger cars and 17.3 mpg for 

light trucks. These values are also from the MOBILE6.2 model.

These emission factors and fuel consumption rates are for gasoline-fueled passenger cars and 

light-duty trucks only. Diesel cars represent less than 0.5 percent of all cars on the road in the 

United States as of 2005, and diesel light trucks represent less than 2 percent of all light-duty 

trucks on the road. In general, diesel vehicles (relative to gasoline vehicles of similar size and 

age) will have lower emissions of HC and CO, and higher emissions of NOx and particulate 

matter. Diesel fuel economy tends to be better than that of similar gasoline-fueled vehicles, 

meaning total fuel consumption and CO2 emissions per vehicle per year tend to be lower.

Changes from Previous Versions of this Fact Sheet

The emission factors presented below are not directly comparable to those used in previous 

versions of this fact sheet due to the extensive changes made to the MOBILE model in order 

to better represent real-world driving. In earlier versions, the emission factors were based on 

an average travel speed of 19.6 miles per hour (mph). This is the average speed of the Federal 

Test Procedure (FTP), which is the basis for certification of new vehicles to applicable emission 

standards. The FTP is considered to be reasonably representative of overall traffic in urbanized 

areas; it includes stops and starts, idling time, accelerations and decelerations, and short cruising 

stretches. However, it does not include any acceleration or deceleration rates greater than 3.4 

mph per second (mph/s), nor does it include any travel at speeds greater than 60 mph.

The emission factors produced by MOBILE6.2 are based on national average data on the fraction of total vehicle miles traveled (VMT) accrued on each of four major roadway types, and 

national average traffic speeds associated with each of these facility types. The four roadway 

types are limited access highways (freeways, expressways), ramps (entrance and exit ramps to 

and from limited access highways), arterials (primary surface roadways), and local and collector 

roads (local streets and minor surface roadways). 

These emission factors account for the fact that a single value of average speed is not adequate 

for the characterization of real-world driving patterns. For example, driving patterns associated 

with an average speed of 40 mph on a limited access highway are not the same as driving patterns associated with an average speed of 40 mph on an arterial route; in the first case, 40 mph 

implies heavy traffic with some congestion and varying speeds, while in the latter case 40 mph 

represents near free-flow conditions. The emission factors developed for the four roadway types 
Emission Facts

include much sharper acceleration and deceleration rates (up to 6.9 mph/s), which result in 

significantly higher emission rates for short periods of time, and higher maximum speeds (up to 

75 mph on limited access highways).

Thus, these emission factors differ from those that would have been estimated using previous 

versions of the MOBILE model, which assumed a single driving pattern with an average speed of 

19.6 mph, no accelerations or decelerations exceeding 3.4 mph/s, and no driving over 60 mph. 

These newer emission factors are much closer to being representative of observed real world 

driving patterns and speeds, and thus more accurately represent emissions in use.

Average Emissions and Fuel Consumption for Passenger Cars*

Pollutant/Fuel

Emission & Fuel

Consumption Rates

(per mile driven)

Calculation

Annual 

Emission & Fuel 

Consumption

VOC 1.034 grams (g) (1.034 g/mi) x (12,000 mi/yr) x (1 lb/454 g) 27.33 lb

THC 1.077 g (1.077 g/mi) x (12,000 mi/yr) x (1 lb/454 g) 28.47 lb

CO 9.400 g (9.400 g/mi) x (12,000 mi/yr) x (1 lb/454 g) 248.46 lb

NOx 0.693 g (0.693 g/mi) x (12,000 mi/yr) x (1 lb/454 g) 18.32 lb

PM10 0.0044 g (0.0044 g/mi) x (12,000 mi/yr) x (1 lb/454 g) 0.12 lb

PM2.5 0.0041 g (0.0041 g/mi) x (12,000 mi/yr) x (1 lb/454 g) 0.11 lb

CO2 368.4 g (368.4 g/mi) x (12,000 mi/yr) x (1 lb/454 g) 9,737.44 lb

Gasoline 

Consumption 0.04149 gallons (gal) (12,000 mi/yr) / (24.1 mi/gal) 497.93 gal

*See Endnotes
Emission Facts



Average Emissions and Fuel Consumption for Light-Duty Trucks*

(most pick-uptrucks, SUVs, etc.)

Pollutant/Fuel

Emission & Fuel

Consumption Rates

(per mile driven)

Calculation

Annual 

Emission & Fuel 

Consumption

VOC 1.224 grams (g) (1.224 g/mi) x (15,000 mi/yr) x (1 lb/454 g) 32.35 lb

THC 1.289 g (1.289 g/mi) x (15,000 mi/yr) x (1 lb/454 g) 34.07 lb

CO 11.84 g (11.84 g/mi) x (15,000 mi/yr) x (1 lb/454 g) 312.95 lb

NOx 0.95 g (0.95 g/mi) x (15,000 mi/yr) x (1 lb/454 g) 25.11 lb

PM10 0.0049 g (0.0049 g/mi) x (15,000 mi/yr) x (1 lb/454 g) 0.13 lb

PM2.5 0.0045 g (0.0045 g/mi) x (15,000 mi/yr) x (1 lb/454 g) 0.12 lb

CO2 513.5 g (513.5 g/mi) x (15,000 mi/yr) x (1 lb/454 g) 13,572.69 lb

Gasoline 

Consumption 0.05780 gallons (gal) (15,000 mi/yr) / (17.3 mi/gal) 693.64 gal

*See Endnotes

For More Information

The other fact sheets in this series and additional information are available on the Office of 

Transportation and Air Quality’s Web site at:

Emission factor fact sheets: www.epa.gov/otaq/consumer.htm

Modeling and estimating vehicle emissions: www.epa.gov/otaq/models.htm

Fuel economy: www.epa.gov/fueleconomy

 www.fueleconomy.gov

Improving fuel economy and reducing emissions: www.epa.gov/epahome/trans.htm

 www.fueleconomy.gov/feg/drive.shtml

Finding the “greenest” vehicle: www.epa.gov/greenvehicles
Emission Facts



Endnotes

1. Figures presented above are averages only. Individual vehicles can differ substantially in 

terms of both annual miles traveled and pollution emitted per mile from values indicated here. 

Values shown may differ slightly from original sources due to rounding.

2. These emission factors and fuel consumption rates are averages for the entire in-use fleet 

as of July 2008. Newer vehicles generally emit less pollution and use less gasoline, while older 

vehicles generally emit more pollution and use more gasoline. This is due to several factors, 

including the increasing stringency of emission standards over time and the deterioration (degradation) in the performance of emission control technology (e.g., catalytic converters) with 

increasing age and accumulated mileage.

3. Carbon dioxide (CO2), while not regulated as an air pollutant, is the transportation sector’s 

primary contribution to climate change. Carbon dioxide emissions are essentially proportional 

to fuel consumption (and inversely proportional to fuel economy) – each 1% increase in fuel 

consumption results in a corresponding 1% increase in carbon dioxide emissions. About 19.4 

lb CO2 is produced for every gallon of gasoline combusted. Passenger cars and light-duty trucks 

also emit small amounts of other greenhouse gases (GHGs); thus, total GHG emissions 

from these vehicles are slightly greater than the CO2 emission totals shown in this fact sheet.

4. All of the emission estimates provided in this document are consistent, in terms of assumptions made and modeling methodology, with those provided in the other fact sheets in this 

series: “Idling Vehicle Emissions” (EPA420-F-08-025), “Average In-Use Emission Factors for 

Urban Buses and School Buses” (EPA420-F-08-026), and “Average In-Use Emissions from 

Heavy-Duty Trucks” (EPA420-F-08-027).