People buying a car now have a new tool to help figure out which are easiest on the environment.
The air conditioner in your car uses a chemical that's a super greenhouse gas -- more than a thousand times more potent than carbon dioxide.
Cars leak a little of this gas, and some cars leak more than others.
The Minnesota Pollution Control Agency has a Web site that lists the leakage for all new-model cars and trucks.
MPCA scientist Barbara Jean Conti said, compared to the CO2 you emit from the gas you burn, it's not a lot. But it's something to consider.
"There's so many cars, and this chemical is so much more potent than carbon dioxide, that's where we see the effect," she said.
The website also links to a green vehicle guide from the U.S. EPA.