He leaves them idling as they wait for him in the morning. He could walk 5 minutes to the closest train station but for some reason decides to take the SUVs. The SUVs are 2007 Flex Fuel Chevrolet Suburbans. He uses Ethanol in New York and whenever he can when he travels. Even on E85, the fuel economy for the Suburban is horrible. EPA ratings 4WD and 2WD are as low as 10 and 14 MPG for the city.
The SUVs are "selected, owned, and maintained" by the NYPD. While the mayor's staff won't confirm, I think it's a security issue. I mean, look at that thing! I think bullet proof is a standard option.
[Source: New York Times]