As the Trump administration works to finalize new regulations to freeze fuel economy and emissions at 2020 levels, another company may be ready to join California's voluntary efficiency targets that came to light this past July.

According to a report Tuesday from The New York Times, Mercedes-Benz plans to sign on to the rules. The newspaper cited two people familiar with the company's decision making but did not say when the German luxury brand may make the news public. Should Mercedes agree to the California rules, it would be the fifth company to do so.

Ford, Volkswagen Group, Honda and BMW all agreed to the rules this past July in an announcement that took the industry by surprise. Compromise discussions between California and the Trump administration broke down in the past as the upcoming federal regulations may strip the state's rights to set its own regulations.

The current rules, put in place during the Obama administration, call for fuel economy averages to rise to 54.5 mpg by 2025. California's deal with automakers places average fuel economy targets at roughly 50 mpg. More than a dozen other states follow California's fuel economy and emissions rules, which makes automaker support crucial.

While Mercedes-Benz is reportedly close to signing on with California, the Trump administration supposedly called General Motors, Toyota and Fiat Chrysler Automobiles for a White House meeting and urged the companies to back the administration's proposal. By freezing fuel economy standards, the administration argues automakers will have less regulatory burden and be able to keep vehicle costs down. Meanwhile, The Times reported a sixth automaker is interested in joining the California pact.

We should see the Trump administration's final proposal on fuel economy and emissions around Labor Day. If it's not up to snuff for California, prepare for lawsuits.