I've gone beyond 0 once as well. I went for a drive with a group that included two heavily modified M3s, and was on a long, fast uphill mountain road. I had about 1/2 of a tank at the bottom and figured that was plenty for a 20mi or so road. I was on the throttle pretty heavily to keep them in sight, and not paying attention to my gas gauge.
When we got to the top, I looked down and my gas light was on and displaying about 5mi left in the tank. Fortunately it was downhill all the way back to the gas station.
When we got to the top, I looked down and my gas light was on and displaying about 5mi left in the tank. Fortunately it was downhill all the way back to the gas station.