Reports Offer Fuel Economy, Operational Cost Information For Vehicles

Honda Motor Co.'s vehicles posted the highest average fuel economy for 2005, according to EPA.

On July 28, EPA released its annual report, "Light-Duty Automotive Technology and Fuel Economy Trends: 1975 Through 2005." The report provides data on the fuel economy and performance characteristics of light-duty vehicles (cars, vans, sports utility vehicles (SUVs) and pickup trucks) for model years 1975 through 2005.

The Honda fleet averaged about 25.1 miles per gallon (mpg), followed by Toyota, with a fleet average of 23.5 mpg. In third place was General Motors, with 20.5 mpg, then DaimlerChrysler with 19.8 mpg. The lowest average posted was Ford at 19.5 mpg.

Since 1997 fuel economy has been relatively constant, ranging from 20.6 to 21.0 miles per gallon (mpg). Model year 2005 vehicles are estimated to average 21.0 mpg. This is 0.2 mpg higher than 2004, but five percent below the fleet-average fuel economy peak value of 22.1 mpg achieved in 1987. According to EPA, this increase is due in large part to the increase in fuel economy standards for light trucks and SUVs implemented in 2005, offset in part by the increasing popularity of less fuel-efficient light trucks, particularly SUVs. This year, cars and light trucks are each projected to account for 50 percent of vehicle sales. While fuel economy levels have been relatively constant, vehicle performance (e.g. acceleration) and weight have nonetheless increased.

Recent technology developments, such as hybrid-electric vehicles, clean diesel technology and variable displacement engines hold promise for the near-term future, according to EPA. 

If you are considering purchasing a heavy-duty vehicle, a report prepared by TIAX LLC, a leading product and technology development firm, for the California Natural Gas Vehicle Partnership (CNGVP) suggests that heavy-duty natural gas powered vehicles that meet strict emissions standards are more cost effective to own, operate and maintain over their lifetime than comparable diesel powered vehicles when the price of crude oil is more than $31 per barrel.

"The findings of our report are significant," said Mike Jackson, Senior Director, TIAX LLC. "Transit, refuse and short-haul fleet managers should carefully evaluate natural gas and diesel vehicle technologies that meet 2010 emissions standards. For these applications, our study indicates vehicles equipped with stoichiometric natural gas engines and three-way catalysts will have similar owning and operating costs compared to diesel engines equipped with advanced aftertreatment technologies, which enable both sets of vehicles, respectively, to meet new emissions standards.

"That said," Jackson added, "at oil prices above $31 per barrel, natural gas technologies are cheaper than the diesel alternatives and may well be the best overall option for fleet managers."

Projections of diesel vehicle costs have "a higher range of variation" than natural gas vehicle costs due to "uncertainty in the diesel engine technology and emission control equipment needed" to meet the performance demands of 2010 heavy-duty applications, according to the TIAX report.

Gunnar Lindstrom, CNGVP chairman, a coalition of public- and private-sector interests that commissioned the report, welcomed its findings. "Diesel engines have had a significant cost advantage over natural gas up to now, but the costs of owning and operating comparable vehicles that meet 2010 emission standards, coupled with the price of petroleum, shifts the advantage to natural gas. What's more, natural gas vehicle manufacturers are now taking orders for vehicles that meet 2010 emission requirements, while uncertainties remain about diesel vehicle costs and technologies. This is solid justification to increase deployment of natural gas vehicles in California and across the country."

However, the Diesel Technology Forum sharply criticized the report, saying the research attempts to suggest compressed natural gas vehicles may cost less to operate in the future, but takes absolutely no account of how the CNG fuel actually gets into the tank.

"It's impossible to develop a valid cost comparison between diesel and natural gas vehicles without considering the infrastructure costs necessary to support natural gas fleets," said Allen Schaeffer, executive director of the Diesel Technology Forum. "That means you have to add in the cost for building the shipping and receiving facilities, pipelines, fueling stations and maintenance facilities that currently do not exist."

Schaeffer cites as proof of the need for infrastructure a paragraph from the CNGVP press release which points out there are only 1,500 natural gas filling stations in all of North America. That's comparable to more than 69,000 diesel stations in the United States alone.

These infrastructure challenges affect the availability of natural gas, which has an impact on cost that is not considered in the CNGVP report. Increasing the demand with no clear way of increasing supply will only increase that cost, Schaeffer said.

"Costs for distribution, compressors, fueling stations and the special maintenance facilities required to safely work on natural gas vehicles -- or the impact on gas prices without those systems -- must be part of the equation," Schaeffer said. "In many parts of California and the nation, those costs are simply prohibitive without substantial government subsidies, which is why we continue to call for keeping a diverse suite of fuel options open for the marketplace."

This article originally appeared in the 08/01/2005 issue of Environmental Protection.

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