I have run past the bars disappearing several times and haven't once been close to empty. My last tank I ran 30 miles beyond the last bar and only needed 10.6 gallons of
fuel (providing the pump was accurate). And that was a tank that went for 713 miles.

I live in a colder climate (near Buffalo, NY) . I finally reached a 500 mi tank in April with 53 mpg. As it continued to warm up, I reached a 600 mi tank in mid May. My lifetime mpg is still climbing with each tank. Tank # 18 was 631 mi - and I put gas in to the scond click (usually I stop at the first click). I generally average around 10.3 gals when I fill up - but on this tank (11.2 gals) I had gone about 40 miles after reaching 0 bars. Sooo... now I'm thinking. If I have a great tank going (high 50's mpg), and I have a little extra gas in the tank (I filled to 2nd click), and I push the envelope (with 0 bars I figure around 2 gals of gas in the car - then maybe a 700 mi tank is possible. On Tank 19 I was showing around 58.6 mpg ( I generally do 1.4 more - so 60.0 mpg) whenI got to 0 bars with 630 miles on the tank. If my rough math was correct, I should be able to go another 100 miles or more. So I decided to go for the 700+ tank. For insurance, I put a new one gallon tank of gas in the trunk!

On 6/15/06 I put 700.5 miles on tank # 19 . I clicked off at the 1st click, and used 11.24 gallons (still not a full tank ?). This was my best tank ever at 62.3 mpg. I was a bit nervous, and will not do this again.

I would expect that sooner or later some one will make an 800 mi tank. If you average 65mpg and use all the gas it could be feasible. I noticed that our mpg leader has put 12.9 gallons of gas in his/her tank. Oops, When I looked again, I saw that the car "papaya" has allready made four 800+ mile tanks.

Don
Best tank 67.5 mpg (555.5 mi.)
Best trip 91.5 mpg (42.2 mi.)