I can say this. I was stopped in the middle of winter one time in pennsylvania on I-81 in a snow storm, which an oil tanker had wrecked on the interstate.. I was part of a 3 lane back-up and no where to go. I had no choice but to leave my Montero Idling so I didn't freeze to death. I must have left it running for easily for 4 hours while they cleared the pile up and cleaned up the mess, and then clear the highway/de-ice the hill.

I figured out I only burned 3 gallons of fuel at most. I had tanked up in Hazleton when I saw the weather getting bad (never travel in snow storm on a low tank) I tanked back up when I got food at Sheetz in wilks-barre after it started moving again and I couldn't put more than 4 1/2 gallons in it.

Needless to say I was impressed how efficient the 3.0 is idling in the cold like that. 1 Gallon per hours is definitely unrealistic.