I always fill up when the gauge is about 1/8 empty and it usually takes 19 or 20 gallons to fill up, the manual says it has a 21 gallon capacity. Does any one know what the tank reallydoes hold and is there a low fuel warning?

 

I assume you mean 1/8 full. I think it is a 26 gallon tank. can't quite remember....and yes there is a low fuel indicator light.

 

23 Gallon tank.

 

Yeah, you get a nice scrolling reminder on your "DIC" as GM calls it once your reach the threashold, which seems to be about 3-4 gallons based on my fillups.

 

I rarely let it go below 1/4 tank.. usually filling up at 1/2 way or sooner and if I'm traveling I fill'er up while she sits, especially as we're moving into cooler weather and being in Texas. Once the temps stabilize a bit I'll refill around the 1/4 mark. With warmer humid days suddenly swinging to a cold day you can getsome nice water in your tank. My old Mazda truck really loved it when this happened and rewarded me with stalls, chuggy response and a glowing "check engine light" for a few days until the water got out of its system. Not sure how sensitive HUMMERS are to this yet since I just got mine in August.