[Ron Mummert]

This question has been kicked around for years. As I recall, from some old posts, the float device in the tank is made of some sort of material that absorbs gas, gets heavy, thus "sags", giving a pessimistic reading throughout its range. Typically when you hit the empty line, there's probably another 80-100 miles left for your driving pleasure. On a trip long ago with gentle driving most of the time, I squeezed 400 miles out of the tank before the "low" light did its thing. I drove another 20 miles to a station, filled her up, & only managed to cram in about 17 gallons. Assuming I was getting roughly 25 mpg, an 18 gallon tank would be good for 450 miles.

Ron.