Lyft is backing a legal challenge against a key part of the Trump administration’s plan to weaken fuel emissions standards for the auto industry. The ride-sharing company filed a brief in federal appeals court Thursday in support of a lawsuit against the Environmental Protection Agency (EPA) for concluding that standards set during the Obama administration for the years 2021 through 2026 should be weakened. “Lyft relies on EPA’s greenhouse gas standards both to reduce fuel costs for drivers and to help make its rides carbon-neutral,” the company wrote in its brief. “Drivers that use Lyft need fuel-efficient cars to make the service more economic, and both Lyft and its riders count on that fuel efficiency to reduce costs and protect the environment.” Lyft announced last year that it was investing in offsetting the emissions of its worldwide fleet of cars in order to become carbon neutral. It’s joining a coalition of green groups and Democratic states led by California in challenging the initial step of the Trump administration’s weakening of the Obama-era standards. The Trump EPA has not yet finalized its new standards. Opponents argued that the agency violated procedural requirements in making the April determination. Lyft says that weakening the standards will hurt its business. “Lyft must rely on the automotive industry to make fuel-efficient vehicles prevalent and affordable,” the company wrote. “That will only happen if automakers invest in efficiency-increasing technologies, and that investment is most likely if EPA has future standards on its books today that drive that change.” In November, a three-judge panel for the D.C. Circuit Court of Appeals denied the EPA’s request to dismiss the lawsuit. The court has not set a date for oral arguments.