How long will a car run on 1 gallon of gas (while not drivingn, just idling)?

here is what I could find from cartalk.com

so i guess about 6 hours or so.

The only statistic we've ever seen for the amount of fuel used at idle is from the Ohio Air Quality Development Authority. It says that the average car uses about 0.15 gallons of fuel per hour of idling. That's about 45 cents' worth of gas. If you do that once a day for 250 days a year, that's $112.50 a year at $3 a gallon.

TOM: So what you need, Steve, is a jack. Jack up one of those front wheels while you're stopped and doing your work, put that baby in drive and let the odometer roll. That way, you'll MAKE money on the reimbursement for your idling time.

RAY: No, that's dishonest, Steve. And that doesn't even take into account the excess pollution you're creating by idling for an hour a day. A better solution would be to stop at a Distended Belly Doughnut Shop and do your work in there over a cup of iced coffee.

TOM: Yeah. It's got to be a lot more comfortable than sitting in your car. You won't waste any money burning gas, you won't be creating new pounds of carbon dioxide and you can put the coffee on your expense report. What could be better than that, Steve?

possibly 2 hours,1/2 gallon hr if tuned right

Zero miles!

get a grip!!! thats like how long will a totsie pop last...duh!!!