On the show Real Time with Bill Maher (Jan 9, 2015), Jay Leno (a guy that seems knowledgeable about cars) made this very interesting statement 37 minutes in:
A 1977 Ford Galaxy, one of those big ones. Park it on the street, with the engine off...pollutes more than a Ford Fusion going down the road at 60 miles an hour.[...]Because A) the gas tank is [unclear part] vented, closed, so it just goes to atmosphere. The plastic used, ever notice old cars when they sit in the sun, the windshield gets all clouded up, and it's grease because it's gas, it's toxic gas, coming off the plastics and the oil used to make that. They don't use any of that anymore.
Transcription was made by myself so you'll have to bear with it. We could probably compare a car from the 70s versus a recent one.
Does anyone have any source for such a statement? Maybe some numbers backing this statement. I assume that Jay Leno didn't consider the manufacturing of the new car or the recycling of the old one, so that part can be ignored. I would assume one could only consider atmospheric pollution.