you refer to for instance those US Postal service LLV's that do 10 miles to the gallon (converts to 4.3 km per liter)?

https://www.reddit.com/r/todayilearned/comments/3xqc4m/til_t...

There isn't any legally binding cap on on climate emissions in the U.S.

There are some energy efficiency laws, but aside from that we don't really have any climate laws at all.

In the land of the blind...