As it prepared for its "cash-for-clunkers" program, the government rejiggered gas mileage figures on about 100 older vehicles last week in a way that changed whether they would be eligible for up to $4,500 in sales inducements.
The Environmental Protection Agency says the changes resulted from a double-check of its fuel-efficiency ratings on more than 30,000 1984 and newer vehicles in advance of the official start of the clunkers program Monday.
About half the 100 suddenly did not qualify because their combined mileage rating was revised upward; others unexpectedly got in.
"As a result of the review, roughly an equal number of vehicles became eligible as those found to be not eligible," said the EPA in a statement. "Eligibility for about 100 vehicles was affected."
Car-shopping website Edmunds.com said Monday that it discovered the switcheroo because potential buyers were complaining on its discussion boards.
Some said it made them ineligible at the last minute for car deals they already had on deck.
"We had everything lined up. We had a couple car dealers that had verified our car qualified, and we were ready to purchase a new car this weekend," wrote one potential buyer, identified on the site as John1152. "But it will not happen now because at the last second the EPA updated the information at their web page for a 1993 Toyota Camry wagon ... from 18 mpg to 19 mpg."
Karl Brauer, editor in chief of Edmunds.com, said, "It's unfortunate that consumers who had been researching and planning to trade in their vehicle ... are now left in the dust."
To qualify for the $1 billion program aimed at spurring auto sales and driving gas guzzlers off the road, the clunker must have an EPA city-highway "combined" rating of 18 miles per gallon or lower.
Buyers then get a $3,500 incentive if the new car gets 4 to 9 mpg more or $4,500 for 10 mpg or more. The new car also must itself have a minimum 22 mpg combined rating. The program ends Nov. 1, or when the $1 billion runs out.
EPA gave no reason its ratings were inaccurate or why some went up. For the 2008 model year, EPA started revising mileage figures, typically downward, to better reflect real-world driving. For example, a Toyota Prius that had been rated 60 mpg in city driving fell 20% to 48 mpg.