Mpg

[Chris Ingerman]

Anyone happen to know how many gallons of gas you have when the gas light comes on? I drive a 99 silverado 1500 5.3L v8.

[Sharpz]

On my 99 silverado extended cab, 2 wd, with the 5.3 I have pushed it to 30 miles before once the light came on.  Some of that was highway miles, no hills, and only 1 or 2 stop lights.  All of that matters.  

[CamGTP]

Every truck is likely to be slightly different because of the fuel pump and the level sender. I rough guess is that you should have about 3 gallons of fuel left in the tank when the light comes on.

[dna9656]

It doesn't really matter, you need gas so go get it.

[Supreme Pizza]

I have had several full size Chevys. They usually read empty on the gauge or trigger the fuel light when there is anywhere between 1 and 4  gallons left in the tank. I used to keep a can of gas at home just in case I was getting too low. Now I just fill the tank any time its at 50% or less - which have proven to work very well for me. Keeping the gas tank empty or keeping it full costs the same amount of money in the long run, and a full tank is far less stressful than an empty one.