So today on the way home there was a nice road, no one on it and i figured my baby had been warmed up for awhile ago at about 10mph i gunned it and chirped it into second, no over-rev, smooth shift etc. At the time i was at half a tank with about 110 miles on the trip. Once i was done with about 1/3d of second gear i heard a beep, so i looked down at my dash and it said "34 miles till E" Um.. wtf i've been averaging about 18 miles to the gallon and i just had a half a tank and now i have a little under 1/4th. So.. what happened?