Examining Your Vehicle Fleet

There has been a lot of talk lately about SUVs both in fleets and being driven by the public. When looking at pollutant emissions, it is more complicated then merely looking at the type of the car. There are several factors to consider: the age of the vehicle; the type of the vehicle; the weight of the vehicle; and the vehicle’s gas mileage. All of these important factors need to be studied when determining which vehicles release more pollutants and should be replaced in your fleet. Much of this stems from when different automotive emission control standards were adopted and became effective.

The history of motor vehicle emission standards dates back to the 1950s when a California researcher determined that motor vehicles contributed to a growing air pollution problem. Congress adopted the first major Clean Air Act in 1970 which established the U. S. Environmental Protection Agency and gave the agency responsibility for regulating U.S. motor vehicle emissions. The Clean Air Act required a 90% reduction in hydrocarbon (the Volatile Organic Compound (VOC) of automotive emissions), Carbon Monoxide (CO) emissions, and NOx emissions over uncontrolled levels by the 1975 model year. (At that time the technology did not exist to meet those standards, but the Clean Air Act provided the incentive necessary for the automotive industry to develop the technology needed to clean up vehicle emissions.) By 1975, the automobile industry responded by developing the first catalytic converter and with it unleaded gasoline, in response to VOC (HC) and CO standards.

In 1977, Congress amended the law and mandated that automobiles meet the more stringent standards set in the Clean Air Act by the 1983 model year. In 1981, new cars met the amended standards for the first time. In 1990, Congress further tightened the standards beginning with the 1994 model year called "Tier 1 standards". The 1990 Clean Air Act Amendments also gave the EPA authority to place more strigent standards on light-duty vehicles beginning in 2004. In 1999, EPA adopted the "Tier 2 standards" that require more substantial emission reductions from automobiles, pick-ups, vans, and sport-utility vehicles to be phased in between 2004 and 2009.

As you can see automotive emission standards have significantly changed over the years for all vehicle types. While it is important to realize that SUVs and light duty truck standards are not equivalent to the passenger car standards, one must also evaluate the age of the vehicle, vehicle mileage, weight and gas mileage to properly evaluate your fleet. For example, a new SUV may actually be producing less emissions than an old sedan. So you may be better off replacing that old sedan.

If you are taking the next step, and are evaluating the purchase of vehicles, it is wise to consider whether a new SUV is warranted. If your business can do with a sedan, a new sedan will pollute less than a new gasoline powered SUV (at least for the near future). And better yet, have you looked into alternative fuel vehicles like the new hybrids?

Chart 1 below details the federal EPA exhaust emission standards. You can use this chart as a guide in determining your fleet’s emissions.

^(a) Non-methane (reactive) hydrocarbons.
^(b) Grams per mile.
(c) 5/50 or 5 year/50,000 miles. (Generally vehicles with greater mileage will generally have higher emissions)
^(d) 10/100 or 10 year/100,000 miles. In use compliance is 7/75,000.
^(e) 11/120 or 11 year/ 120,000 miles. In use compliance is 7/90,000.

In order to determine your fleet’s green house gas emissions and gas mileage, and approximate fuel costs visit the Department of Energy’s/U.S. EPA’s website: www.fueleconomy.gov

The Department of Environmental Protection has performed an evaluation of its fleet to best determine which vehicles should be replaced first. We also looked at the actual emission test results in brackets.

Fleet Vehicle Emission Estimation Chart

* assumes 15,000 miles/year.

^(a) GHG= green house gas emissions-CO2 equivalents (tons/year). Source is Department of Energy website: www.fueleconomy.gov
^(b) grams per year
^(c) VOCs=non-methane (reactive) hydrocarbons.
^(d) data obtained from exhaust standards from heavy duty trucks less than 14,000 lbs.
^(e) data obtained from USEPA light duty truck exhaust emission state standards.
^(f) assumes 15,000 miles per year- 45% highway/ 55% city.

Note: Jeep Cherokee weight class is 3700 lbs.– therefore, they are considered light duty under 3750lbs.

Note that the Ranger, which is smaller, is in the same weight class as the F150 (but the emissions is probably at the low end of that class whereas the emissions of the F150 is at the high end).