City records show that this year, the number of cars failing emissions tests jumped from 1 percent to 8 percent by the time the company Systech was hired in July. Systech brought in new testing software and the failure rate came down, but it is still higher than before at 4 percent.
The figure means that about 20,000 cars in Davidson County are failing the tests, according to I-Team calculations.
Metro Councilman Charlie Tygard said he got a surprise failure because of his gas cap.
"I think it's really strange to go from 1 percent to 8 percent to 4 percent within the space of four months. I think we need to get a handle on that,” said Tygard.