Questions and answers about U.S. fuel economy standards

The U.S. government has issued a report on fuel economy and greenhouse gas standards for U.S. cars and trucks that were first established in 2012. The report kicked off a two-year review process leading to a government decision on whether to leave the standards in place through 2025 or change them.

Here’s a look at the standards:

What are CAFE and GHG standards?

CAFE (Corporate Average Fuel Economy) and GHG (greenhouse gas) standards are mile-per-gallon and emissions targets for cars and trucks set by the U.S. government. The standards are based on size and are weighted by sales. Each manufacturer has a different requirement based on the models it sells.

Congress required CAFE standards in 1975 after several years of gasoline shortages during the Arab oil embargo. The standard for passenger cars stayed at 27.5 mpg from 1990 until 2007, when Congress required increases in fuel economy. At the same time, the Environmental Protection Agency began regulating greenhouse gas emissions. In 2009, the government set a standard of 34.1 mpg for cars and light trucks by 2016. In 2012, the government set a new target of 54.5 mpg by 2025.

Does that mean my car could get 54.5 mpg in 2025?

No. That figure is based on the fuel economy needed to achieve greenhouse gas reductions. Manufacturers can apply credits for various technologies to arrive at that figure. Real-world mileage is likely to be around 40 mpg.

What’s happening now?

The government must decide whether the proposed standards for 2025 should stay in place or be modified. When the National Highway Traffic Safety Administration and the EPA set the new standards in 2012, they agreed to conduct a mid-term evaluation for model years 2022-25. That evaluation begins with the draft technical assessment, which was released Monday, and is expected to end in 2018 with a decision on whether the CAFE standards should be modified.

What did the draft technical assessment say?

It says automakers are well on their way toward meeting the 2012 standards, but it also says those standards might have to be lowered, since low gas prices have changed the mix of vehicles that automakers sell. More people are buying trucks and SUVs — and spurning small, fuel-efficient cars — now that gas prices are low.

Why would the government change the standards?

Gas is more than $1 per gallon cheaper than it was in 2012, when the standards were issued, which has hurt demand for fuel-efficient cars. If automakers can’t sell those cars, then they can’t apply their high mileage toward their corporate average. But environmentalists and others say automakers are already beating the targets in many cases, so the government shouldn’t weaken them. They also say automakers have been pushing SUVs because they are more profitable than cars.

How are automakers improving their fuel economy?

The standards give manufacturers extra credit for new technologies, such as hybrid engines for pickup trucks and stop-start systems, which automatically shut off the engine when the vehicle stops. They also get greenhouse gas credits for more efficient air-conditioning systems.

Do those added technologies make my vehicle more expensive?

Yes. The EPA estimates the fuel economy standards will cost $1,017 per vehicle between the 2022 and 2025 model years, while NHTSA estimates they will cost up to $1,245 per vehicle.