<P> The U.S. Department of Transportation ruled that deals involving cash - for - clunkers trade - ins based on old EPA mileage numbers and consummated before July 24 would be honored, but that deals consummated after July 24 on vehicles that became ineligible as clunkers due to mileage ratings changes would not be honored . </P> <P> Depending on the type of car purchased and "the difference in fuel economy between the purchased vehicle and the trade - in vehicle", the amount of the credit given in the form of vouchers to eligible customers is either $3,500 or $4,500 . New car dealers will be able to reduce the purchase price by the amount of the voucher for which that the customer is eligible . </P> <P> To ensure that vehicles traded - in under "cash for clunkers" will not be resold by dealers, the program outlines a procedure for destructively disabling the engine (and thus also precluding the possibility that any mechanical engine components might be salvaged to be used in the repair of any other vehicles): The motor oil is drained and replaced with a sodium silicate solution, then the engine is started and run until the solution, becoming glass - like when heated, causes engine internals to abrade and ultimately seize . In addition, the salvage or scrap facility which acquires the vehicle cannot sell the engine, cylinder heads or a "rolling chassis" from the scrap vehicle . The salvage or scrap facility can sell any other component (including the transmission and axles) from the scrap vehicle separately and may dismantle and warehouse the parts . The "hull" of the vehicle must be crushed within 180 days . Cut off or unbolt front end assemblies may be saved and sold at a later date, as well as the "top and back" of pickup cabs . </P> <P> The outlined procedure says that running the engine at 2,000 RPM "should disable the engine within a few minutes"; if not, then allow the engine to cool off before repeating the procedure . Hazards associated with the intentional overheating and destruction of the engine include rupturing radiator and hot water / steam, motor oil ejection, toxic fumes, and fire . </P>

When did the cash for clunkers program start