What’s it take to stop drivers from polluting the air with their smoky old cars? A little green, apparently. That was the simple thought behind a North Texas plan aimed at getting older cars off the road to help the Dallas/Fort Worth region improve its air quality and meet EPA mandates.

The AirCheck Texas Repair and Replacement Assistance Program – also known as Drive a Clean Machine – began offering drivers cash vouchers of $1,000, later upped to $3,000, replace their aging, exhaust-belching clunkers with newer, cleaner vehicles.

To qualify Texas motorists had to have cars that were at least 10 years old, and lower than average incomes (up to 300 percent of the poverty level).

Turns out this demographic was hardly a niche market. Applicants slammed the program’s phone operators with some 800 calls daily, resulting in nearly 19,000 applications. And by the time all the new cars are purchased, some 8,500 old high-polluting vehicles will be off the roads, according to the North Texas Council of Governments which administers the state-funded program.

That will at least nip at the area’s annual summer pollution doldrums that result when exhaust fumes are trapped at ground level by high temperatures, a phenomenon in Sunbelt cities that can wreak respiratory havoc with children, asthmatics, runners and senior citizens.

For the moment, though, Drive a Clean Machine is putting it in neutral as the cash dwindles. The program will temporarily stop taking applications today, but will place applicants on a waiting list in case any more money is available for fiscal 2008.

The good news: Drive a Clean Machine resumes for a second year on Sept.1, with the state’s new fiscal year.