The government sponsored “Cash for Clunkers” has received an overwhelming response all over. The trade-in program, in fact, has proved so popular that people are dumping their gas guzzlers and are switching over to more and more fuel efficient vehicles than ever. Last week, it was widely perceived that the funds allocated for the program may soon get exhausted. However, the government rushed in and pumped another $2 billion which quickly boosted the sales to record levels. The initial $1 billion of funding approved in June for "clunker" business generated more than $520 million in rebates and more than 220,000 in auto sales.   Transportation Secretary Ray LaHood recently said as many as 157,000 trade transactions had been registered, exhausting $664 million of the $1 billion appropriated for the program. Interestingly four of the five top-selling cars are manufactured by foreign automakers, according to new data released by the federal transportation officials. More than 80 percent of the vehicles turned in are trucks and sport-utility vehicles. Ford Focus has been the top-selling new car followed by the Toyota Corolla, Honda Civic, Toyota Prius and Toyota Camry. The new vehicles sold under the program, on an average, deliver 25.4 miles per gallon, compared with an average of 15.8 mpg for the trade-ins.   Officially called the Car Allowance Rebate System or CARS, the “Cash for Clunkers” program is designed to help the economy and the environment by spurring new car sales. Car owners can receive federal subsidies of up to $4,500 for trading in their old cars for new ones that achieve considerably higher gas mileage. The Congress approved the CARS program in mid-June, and the program is scheduled last until November 1 or when the funds run out.   With a huge and growing demand for fuel efficient cars, the Asian carmakers are smiling because most of the smallest and most fuel-efficient vehicles are manufactured by them. Domestic manufacturers like Ford have also registered record sales. Overall, the program has been a huge hit than expected and has been highly instrumental in stimulating demand for both foreign and domestic vehicles. Though some dealers complain that they are troubled with the paperwork to get reimbursements, the program has indeed spurred interest in new cars as well.   Meanwhile, Chrysler has gone a step ahead and announced a month-long program to spur sales by offering an additional $4,500 for trade-ins regardless of whether or not the old vehicle meets federal requirements for the rebate system. For buyers looking for better financing instead of cash, Chrysler is offering zero percent APR for 72 months available as well. This offer has further boosted the sales.