That's great news, that the court upheld EPA regs on GHG emissions!  It got
lost under all the talk about the Supreme Court decisions.

The articles don't say anything about regulating auto emissions - they are
focused only on power plants.  But for those concerned about GHGs emitted
by your vans, the only way to reduce them is to consume less gasoline.  GHG
emissions are a linear function of gallons of gas burned.

According to
http://www.environment.gov.au/settlements/transport/fuelguide/environment.html,
regular gas emits 2.3 kg of carbon per liter burned and diesel emits 2.7 kg
of carbon per liter.  (Don't ask me how the weight of the emissions can be
greater than the weight of the fuel burned, it doesn't make sense to me
either!)  Burn less gas and you emit less fuel.  So anything that enables
you to consume less gas will reduce your climate change impact.  Less total
gas, that is - if you get better gas mileage and then drive more because
you spend less per mile on gas, you aren't reducing your emissions!

Joy