The US government is proposing to allow engineers to design and build electric vehicles, in a move that could transform the industry.
In a draft proposal published on Tuesday, the Department of Energy (DOE) said it was ready to support small engine repair (SEM) and civil engineering.
In the long term, the US could develop a large fleet of electric cars, which could boost demand for diesel engines.
The DOE said in a draft statement that it would also allow electric vehicle companies to sell fuel cell cars.
The new rule, which was not included in the final document, does not set a specific price, but is expected to raise millions of dollars.
In 2016, the government spent more than $8bn on the purchase of nearly 200,000 EVs, which were the most-sold vehicle in the world.
The rules have attracted criticism from industry groups, including the American Society of Civil Engineers (ASCE).
In a statement on Tuesday it said the rule was “unrealistic, expensive and burdensome”.
“The new rule will put enormous strain on the ability of small business owners to invest in innovative new technologies,” said Michael Evers, chief economist for the Association of Automobile Manufacturers (AAM), a trade group.
The AAM has urged the US government to make its proposed rule “as flexible as possible”.
The proposed rule would also apply to new models, including EVs.
It is the latest step in the US to make electric vehicles more accessible.
In 2015, President Donald Trump ordered a $5bn subsidy to help encourage the development of EVs.
The Obama administration also funded the US Government Electric Vehicle Program (GEVP), which provides grants to encourage the manufacture and sale of electric vehicles.
Last year, a study by the US Federal Energy Regulatory Commission estimated that the US electric vehicle market could generate as much as $5.8bn in revenues by 2020.