Answer:
Gas Gauges are: "Deliberately designed to be inaccurate!
After you fill up the tank the gauge will stay on full for a long
time, then slowly drop until it reads 3/4 full. After that, it
moves progressively faster until the last quarter of a tank seems
to go very quickly. This is a bit of psychological slight-of-hand
to give the impression that the car gets better gas mileage then it
does, it seems to reduce the number of complaints from new car
buyers during the first few weeks after they bought the
car."
"When the needle drops below E, there is usually 1 or
2 gallons left in reserve. To find out for sure, pull out
your owners manual and find out how many gallons of gas your tank
holds, then the next time you fill up an empty tank, check how many
gallons it took to fill it. The difference is your
reserve."
Excerpts from "Understanding
your dashboard gauges" written by Charles Ofria
editor@familycar.com. Used with
permission - 2004.
Please follow the following link to read the full
and very informative article: http://www.familycar.com/Classroom/dashboard.htm.