Fuel range

[MSL2501]

So I've been driving this truck for a while now. I have a 2005 gmc sierra 1500 with the most basic design you can get. No dic buttons, no cruise control nothing. A while back I was driving around and I stopped, got back into my truck and started it when on my information cluster on my dash showed fuel range. I've never seen the fuel range pop up on this truck before. Been driving around for a while and it will just stay even when I shut the truck off and turn it back on. It accurate as well. About a few days ago I bumped the trip button and the fuel range disappeared. I'm kinda disappointed because I liked having a fuel range despite not having those dic buttons. Searched all around and could not find anything on this problem. Just wanna know whether or not this was a glitch or a thing i can actually do.