The US Transportation Department has said that consumers who want to purchase new vehicles not yet on dealer lots can still take part in the 'cash for clunkers' (C4C) program.

The Detroit News reports that consumers have grumbled that many fuel efficient vehicles are in short supply in dealer showrooms.

"Dealers and consumers who have reached a valid purchase and sale agreement on a vehicle already in the production pipeline will be able to work with the manufacturer to receive the documentation needed to qualify for the program," the Transportation Department said in a statement.

If consumers want to order a vehicle under the C4C program, the dealer must obtain the Vehicle Identification Number from the manufacturer before submitting a transaction at cars.gov. The dealer must have all required documentation for the trade-in vehicle in order for the rebate request to be considered, The Detroit News noted.

"The Department of Transportation is trying to make sure that everyone who wants to can participate in this wildly successful program," said Transportation Secretary Ray LaHood.

"Allowing consumers to order vehicles and qualify for the rebate will expand buyers' choices and keep production lines running," he said.