Here is an observation that others may like to know about. The car is a 2013 Impala LT. It slipped my mind that I needed to fill up before work Monday morning. Leaving work I noticed the gas gauge and changed the drivers information screen setting to "miles to empty" which showed 55 miles. I decided to continue driving until I got a "low fuel" warning message. That happened at around 45 miles to empty. I cleared the warning and went back to the "miles to empty" screen. At that point I was going to drive closer to my home to fill up but soon after noticed that the "miles to empty" screen was no longer showing any mileage but was instead displaying " low fuel" where the miles were before. I refueled at that point since I had no reference to go by anymore. The car held just over 16 gallons on fill up. I have never gotten that close to empty but wanted to make sure the low fuel warning was indeed working. I did think it odd that the display would not show miles to empty lower than around 45. Hope this helps someone out.
It is possible the system was designed that way. If you drive on a steep up or down hill grade with very little fuel left in the tank, the fuel in your tank can drain to the front or rear of the tank - causing the pump to lose prime and the engine to stall. Then - your miles to empty is zero.
The fuel pump is cooled by the fuel and can be damaged by running the vehicle empty on fuel, or low enough to cause it to stall.
I suspect the logic behind the software is that, at an estimated 45 miles to empty, the uncertainty of that number is such that you have 45 ± 35 miles to empty - ie, as low as 10 miles or less.
Perhaps such caution is carryover from the past, when these sort of measurements were more pie-in-the-sky than truly reliable numbers.
With today's injected motors, the computer can very accurately keep track of how much fuel has been burned since the last fill-up. But there is still some uncertainty of how much is left. Unless someone at the factory calibrated the level sensor during production, the computer cannot really determine when the pump is going to start sucking air - it's still guessing a little bit at how many miles are actually left.
So, in the interest of caution, at 45 miles left in the tank, the software is sort of going to panic mode and telling the driver "low fuel" meaning "get gas now, just in case".
I suppose, with modern manufacturing processes, the tank making process is more tightly controlled, and the the fuel level sensing function is better characterized, such that there is better estimation of how much gas is left in the tank.
But the old, experienced guys at the factory have told the software guys not to get too trusting of the readings
My 2008 Impala Lt does the same thing. If you keep track of your miles after the 45 miles display changed to low fuel, the 45 miles is fairly accurate of what is left for the distance you can drive.
I own, and have owned, numerous vehicles with the “low fuel” warning system. I have never activated the warning, as I never let my fuel level drop below about one-half tank full.
LOL! I'm just the opposite! And I'm not bragging or being a wise-guy, but for 30 years now I've *always* run all my gas tanks down well past the LOW FUEL warnings - on just about every tank!
I actually use the LOW FUEL warning as a "reminder" that I need to gas up!
When the light comes ON, I look down at the odometer, add a conservative Mileage number for two gallons, and keep driving ... usually passing several gas stations along the way. Depending on the car I'm driving, I've driven to work (25 miles) and then almost all the way back home with the LOW FUEL warning light ON many a time ... FINALLY gassing up only at my favorite station(s)! LOL!
My record with my '02 Impala was 16 gallons poured in! And I have to admit ... I was a little worried those times. Once took a picture and sent it to my siblings, telling them the tank capacity was 16.5 gallons. Don't remember getting any replies. LOL!
Someday I'll probably get burned and that'll "cure" me, but so far I'm perfect.
But I can't do this with anybody else in the car ... they all get frightened to death!
I tested mine to recently, a 2019. Before I went to fill up my gas gauge was on the last bar, as empty. The light never came on. I assume there is a bit more below empty mark but, why no light before. The light does come up during start up. Any thoughts on this?
I have read car companies are super cautious on low fuel warnings from a marketing perspective. Having a bunch of cars sitting on the side of the road out of gas is not a good look apparently.
I've only run mine that low once, at 80KM (50miles) to empty the warning came up on the DIC and stayed on till I hit the check mark then it continued to count down the distance to empty.
I expected it to come on earlier than that, seems like it's cutting it kind of close.
Probably a liability issue. If someone drove until it said, 5 miles to empty, and then the car quit leaving the driver stranded by the side of the road, I could see a bunch of lawsuits.
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