The U.S. Environmental Protection Agency announced a plan in April to make its most ambitious reduction ever to greenhouse gas emissions from U.S. vehicles. As electric vehicles gain traction, the plan has the potential to reshape driving in the U.S., and slow down the effects of climate change.

But new analysis suggests it’s not likely to happen as quickly as expected  combustion engines will have the lion’s share of U.S. roads for a while longer.

The EPA wants tighter pollution standards for cars, light trucks and heavy duty trucks that together would eliminate more than 9 billion tons of CO2 emissions through 2055. It would have the same effect eliminating all current emissions from the U.S. transport sector for five years.

SEE MORE: EPA plans stricter rules for electric vehicles, emissions

The EPA finds that a switch to electric vehicles may be enough all on its own to reduce emissions by proposed levels. Targets could be met if 67% of new vehicle sales were electric by 2032.

But the auto industry, which is already trying to make half of new car sales electric by 2030, says the EPA’s 67% figure an unrealistically high level of sales in such a timeframe.

Meanwhile, analysis from the Associated Press shows that even if electric car sales take off to that extent, some 80% of vehicles on U.S. roads will still be burning fossil fuels.

Regardless, the EPA hopes that by 2055, nearly half of transportation emissions will have been eliminated  and nearly all gas vehicles will be off the road.

The EPA plans to adopt its final regulations in 2024, after gathering feedback from the public and from stakeholders.

SEE MORE: Major automakers announce large electric vehicle charging network

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