So what are they and which one — if any — is right for you?
Environmental Protection Agency
EPA head Scott Pruitt was thought to be eliminating California's emissions waiver, but the Golden State's right to set its own mandates remains in place.
"Climate change is a global challenge. No county can place itself outside of this."
FCA is accused of not revealing software to defeat testing on Jeep Grand Cherokees and Ram trucks.
So, how does that compare with its most obvious rivals?
Automakers' compliance with CAFE may cost 150,000 jobs.
Pruitt's statement is at odds with scientific consensus.
Volkswagen will spend $2 billion over five years to add charging stations across the US and establish a "Green City."
BMW, whose diesel-certification efforts were delayed last year, is getting ready to make diesel-powered cars and SUVs bound for America.
How can the EPA make decisions about renewable fuels if it doesn't have data?
Don't tell the EPA it can't be done.
Volkswagen has had a stop-sale on US diesel vehicles since September, and reached a settlement with the EPA in June.
The EPA and CARB are requesting fuel economy info from Mitsubishi and want the company to do additional testing on some US models.
Amid the aftermath of Volkswagen's diesel scandal, a lawsuit filed Thursday accuses Mercedes-Benz of diesel deceptions involving its BlueTec technology.
VW has a recall plan for the 3.0-liter V6 diesel, but CARB and the EPA still need to test the solution before a recall could start.
FCA is still on the bottom of the fleetwide fuel economy scale, which is why it had to spend big money on emissions credits.
Pickups and larger SUVs have the worst fuel economy of any vehicle types measured in a new report from the Environmental Protection Agency. But before beating up on these gas guzzlers too much, know that's only half the story.