The Ontario government is shifting fees for Drive Clean vehicle emission tests into reverse, lowering the price to $30 from $35 starting in April.
But the Liberal government has no plans to scrap the program that was first introduced in 1999, even though critics say it has outlived its usefulness.
"A very significant portion of domestically caused smog comes from our vehicles – our cars and our trucks – in the province of Ontario," Environment Minister Jim Bradley said Wednesday.
"Drive Clean tackles that."
The program reduces by about a third those emissions in Ontario, which contributes to better health and a better environment, he added.
Drive Clean is supposed to be a revenue-neutral program to get cars that spew pollution off the road, but it is now turning a profit.
The government collected $30-million in fees in 2011-12, but spent only $19-million to deliver the program. It had projected a surplus of $11-million by the end of that fiscal year.
Last year, Ontario's former auditor-general warned that could land the province in legal hot water, because it's a user fee, not a tax. He cited a Supreme Court decision that basically ruled that a user fee cannot exceed the cost to the government of providing the service.
The Liberals promised to lower the charge that drivers pay every two years to get their vehicles tested. The tests are mandatory for light-duty vehicles at least seven years old.
But the Progressive Conservatives say Drive Clean should be eliminated because most cars and light trucks easily pass the test.
The program was "more about the money than it was about the environment," Tory Michael Harris said.
"With cleaner fuels and cleaner cars today, the failure rate of Drive Clean was less than 5 per cent, and it's time for the Drive Clean program to be scrapped," he said.
"No point in tinkering around the edges, lowering fees here and there, let's scrap it altogether."
The New Democrats want to keep the program, but say the Liberals aren't addressing the real problems.
Ontario changed its Drive Clean procedures last January to use onboard diagnostic testing equipment instead of tail pipe emissions, which has led to an average 10 per cent failure rates.
"They're going after the low-lying fruit in order to try to deal with the politics of this issue and not the practicalities of the issue," NDP House Leader Gilles Bisson said.
The Liberals should listen to the auditor so the program actually achieves its goals, he added.
Former auditor Jim McCarter had suggested that the program has outlived its usefulness.
"Vehicle emissions have declined significantly since  and are no longer among the major domestic contributors to smog in Ontario," he said in his 2012 annual report.
"While this is due partly to the Drive Clean program, newer vehicles with improved vehicle-emission-control systems and cleaner fuel requirements have had a larger impact on reducing overall vehicle emissions."
Only light-duty vehicles in non-rural areas within the Windsor-Quebec City corridor are required to take the test, the auditor noted. If it fails, the driver must pay $17.50 for a retest, but that money doesn't go to the government.
British Columbia is planning to phase out its version of Drive Clean next year.