Hawaii is one of 17 states that does not require smog tests or emissions caps for car and truck drivers.
But an environmental group is arguing that the measures could bring the state closer to its clean energy goals.
"It's sad to say we have a problem with those emissions in Hawaii," said Richard Wallsgrove, policy director for the Blue Planet Foundation. "If you look at transportation emissions, they're just not falling year over year the way we need them to."
A recent report by the foundation gave the state high marks for promoting renewable energy sources such as wind and solar and for implementing energy efficiency in commercial buildings and residences. But it gave the state a near-failing mark for reducing fossil fuels in the transportation sector, where motorists' usage of gasoline continues to rise.
"I think a cap is a great idea because we could capture the carbon emissions ... (And) I could see a smog test as a great way to pick out those clunkers," said Wallsgrove.
"They both can be a great idea but they are a platform for a partial solution. They don't give us the whole answer."
Auto repair experts said smog tests can be several times more expensive than a safety check and failure can mean costly repairs.
"You have an emissions test, they say 'Oh man you need a catalytic converter.' That's $3,000," said George Nitta, owner of Nitta's Auto Repair.
That's one reason even proponents of clean energy are hesitant.
State Rep. Chris Lee, chairman of the House Energy and Environmental Protection Committee, said lawmakers are more in favor of incentives for electric cars, which produce no greenhouse gases.
"Instead of going in that direction (of smog tests) ... we're looking at how can we actually get consumers all the way clean," he said.