Reading "o" or empty gas guage
 

I was way late in filling up the tank so, I decided to see how accurate the gauge is.
It went to the warning light coming on at under one red bar left and took 15.8 gallons of gas.
That should leave appox. 2 1/2 gallons left for a "reserve" in our 18 1/2 tank capacity.

if your going to play around with running on empty you would be wise to keep spare gas can in the car so you can run it empty then refill it if you want to know how accurate your own gauge is. I would not assume what is that may not be there.

Why push it? It's been my experience in previous cars that you can "run out of gas" and still have gas in the tank. It's just that the gas line to the engine is not exactly at bottom dead center of the tank. Also, I wouldn't trust the gas at the bottom of the tank to be pristine gas either. If there is any sediment, that's where it would be. Of course Corvettes have a "saddle bag" tank divided into two sections so one side has to back fill the other. It's just not worth tickling the dragon's tail here. Fill it up. Problem (if there is one) solved.

18.6 gallons may be the spec'd capacity but not all of it is usable......

Running extremely low is hard on fueling systems especially for vehicles with an in-tank fuel pumps.

Yes. Fuel cools the pump motor. Fill up when you get to 1/4 tank.

For me the low light comes on and it reports 40 miles to go based on my 20 mpg average. This would indicate that there are 2 gallons remaining but it takes 17 gallons. Honestly its tricky to be that accurate since each gas station's fuel pump shut off is different. Most cut off too quickly in my experience, IE: only 16 gallons go in but then its not 100% full. Plus there is the whole density vs temperature thing.

Just be careful because when the fuel level is low since any high G cornering can leave you sucking air.

I understand your curiosity about the real capacity of your fuel tank. however there a some questions that should remain unanswered. The fuel pumps are, in fact, cooled by the fuel, sediment does settle to the bottom of the tank, and running our of fuel in a fuel injected engine isn't as simple as the old days, with a carbonated engine. 1/4 tank should be the indicator of needing a refuel.

I was going to say something sarcastic about the word (carbonated), but I'll resist. I'm sure its a typo.

Seems appropriate for this thread

Merriam Webster removed carburetor from the language so the word is now carbonated.

My first car was a 72 Cutlass and the first thing I did was upgrade it to a Quadrajet carbonator and dual exhaust.

Wait, wasn't "Carburetor" a big hit for Jim Croce?

2017 Z51 Coupe, 2LT

Last winter we were on a months-long road trip. When buying fuel, I would try to make the purchase when the needle was exactly on one of the major "marks". I was able to get seven readings on each mark, discard the highest and lowest, average the remaining five. I would let the pump click off a second time and stop there. I suspect this was not quite filling the tank, I'm just assuming that these non-aggressive fillups were stopping at 18.0 gallons instead of the official 18.6

With those techniques and assumptions, the fuel in the tank at the various marks would be:
Topped off = 18.0 gal
Full Mark = 16.0
3/4 Mark = 12.2
1/2 Mark = 8.2
1/4 Mark = 5.3
0 Mark = 1.3

"Low Fuel" warning comes on at approximately 50 miles range remaining.
"Range Low" warning comes on at approximately 25 miles range remaining.

There are four small marks on the gauge between each quarter mark, so the small marks each represent indicate about 1 gallon, except between 1/2 and 1/4 where there 4 marks but only 3 gallons.

BTW, I normally fill up at the first opportunity when the gauge gets below 1/2.
:D

Forty years ago I almost ran out of fuel in an airplane with a gauge problem, so I pay more attention than most.

More often than not I find myself filling up before it even gets halfway empty, as I have found that when filling the tank below that point the pump will click off too many times. (I know I could try putting the nozzle in upside down but I'm not comfortable doing that)

Your fuel pump is always sucking from at/near the bottom. It's like any "bad gas" just finds it's way there when near empty.

I agree with the potential pump cooling issue though.

I've found the Fuel Used to be pretty accurate even when using different pumps and their automatic shut-off. If it happens to shut off before the fuel used amount I know I need to add more fuel. I seem to fill up mostly around 15.5 gal.

Okay some of you guys are telling your age here.... :D

Keep doing that and there will be a new fuel pump in your future ! :ack: