I have the same fear, just a blinking last bar, and usually I stop and fill up with about 6.5 gallons, so I believe it comes on when you ahve about 2 gallons left...so even at 30mpg thats 60 miles...but I havent tried it. The CLOSEST I got to "E" was a fill-up for 8 gallons, so I still had 1/2 gallon and the blinking light had been on for about 45-50 miles, so I was afraid to go any farther, and NO other light indicator or WARNING came on...