8200 Americans traded F150 trucks for new ones during the Cash for Clunkers program, rather than eco-friendlier vehicles. Photo / AP

8200 Americans traded F150 trucks for new ones during the Cash for Clunkers program, rather than eco-friendlier vehicles. Photo / AP

WASHINGTON - The most common deals under the US government's US$3 billion ($4.1b) Cash for Clunkers program, aimed at putting more fuel-efficient cars on the road, replaced old Ford or Chevrolet pickup trucks with new ones that got only marginally better gas mileage, according to an analysis of new federal data by The Associated Press.

The single most common swap - which occurred more than 8,200 times - involved Ford 150 pickup owners who took advantage of a government rebate to trade their old trucks for new Ford 150s.

They were 17 times more likely to buy a new F150 than, say, a Toyota Prius. The fuel economy for the new trucks ranged from 15 mpg (6.3 kpl) to 17 mpg (7.2 kpl) based on engine size and other factors, an improvement of just 1 mpg (0.43 kpl) to 3 mpg (1.2 kpl) over the clunkers, or old vehicles.

Owners of thousands more large old Chevrolet and Dodge pickups bought new Silverado and Ram trucks, also with only barely improved mileage in the middle teens, according to AP's analysis of sales of US$15.2 billion worth of vehicles at nearly 19,000 car dealerships in every state.

Those deals helped the Ford 150 and Chevy Silverado - along with Ford's Escape midsize SUV - climb into the Top 10 most-popular vehicles purchased with the government rebates. The most common truck-for-truck and truck-for-SUV deals totalled at least US$911 million.

In scores of deals, the government reported spending a total of US$562,500 in rebates for new cars and trucks that got worse or the same mileage as the trade-ins - in apparent violation of the program's requirements.

The government said it is investigating those reports and said in some cases they were probably entered incorrectly by dealers or based on outdated fuel economy figures.

The new data, obtained by the AP under the Freedom of Information Act, include details of 677,081 clunker trade-ins processed by the government through Oct. 16.

More than 95,000 of the new vehicles purchased under the program - or about one in seven - got less than 20 mpg (8.5 kpl), according to the data.

The new figures, requested four months ago by the AP, represent the first substantial outside accounting of the clunkers program, lauded by the White House and the Transportation Department for improving fuel economy, stimulating sales and taking the dirtiest vehicles off the road.

The data show the average fuel economy was 15.8 mpg (6.7 kpl) for the old vehicles and 24.9 mpg (10.5 kpl) for the new ones. But plenty of consumers bought relatively low-mileage trucks and SUVs with the help of government checks.