GM has reversed its policy and will no longer back Trump's effort to ban California from setting stricter emission rules. Having GM and Ford, the two largest American manufacturers, outline their plan to follow California's wishes will bring more pressure on Toyota, Hyundai, and others to review their positions. 11% of all autos in the US are sold in California and many states have followed that state's lead in setting green mandates.. Gov Newsome has stated an ambitious goal to eliminate all gas powered vehicles in the state by 2035. Would have been interesting to see whether a conservative Supreme Court would've sided with the president over what many considered a states' rights decision.