2000 Dodge Durango 5.9L engine.
How big is the gas tank?
How much gas do i have when the light comes on?

 

Gas tank is 25 gallons. I believe the light comes on with about 4-5 gallons left. However, the gauge in the truck is not very accurate.

 

tank is 16 or 25 gallons (i have never seen one w/ a 16 gallon tank but they were supposedly available)

when the light comes on you should have about 60 miles to empty, however this is a very rough estimate and i suggest NOT running the tank low enough to set to light off as this can overheat the fuel pump if you do it too frequently, and will suck any dirt/debris into the filter and pump cau sing all sorts of problems

 

Mine comes on at 45 miles to go, but I only did that twice in the last 5 years. I don't like running it low because of getting trash off the bottom of the tank. The filter is in the tank so replacing it is fun.

 

Never trust the overhead console for anything... Mine says 5 DTE when i am flat out of fuel!

As for the low fuel light, the miles you have left after the light comes on is gonna very for all of is as there are many factors to consider mainly driving habits of the driver or drivers. I also agree with the others don't allow you tank to get really low. I usually don't drive mine that much or very often so i try to fuel up when i am between 1/4 -1/2 a tank unless they are calling for a major storm then i go ahead and fill it up...