President Trump’s administration has fought to roll back Obama-era vehicle emissions standards since his inauguration, and a final version of the looser rules is expected to be revealed later this summer. But since the rollback faces a number of obstacles — likely including a long, drawn-out battle in the court system that could ultimately kneecap the effort — the administration has found another way to discourage automakers from increasing the fuel efficiency of their vehicles: lower the fines for missing the targets.
Source: https://www.theverge.com/2019/7/15/20695407/trump-vehicle-emissions-rollback-fines-epa-nhtsa