Very non-linear G70 fuel gauge

[Husky]

Have others noticed how non-linear the G70 fuel gauge is? It's pretty annoying. For example, I recently got 165 miles on the first half-tank, but then when it read one quarter tank left, I had only gone another 30 miles! Then, on another full tank where I did more highway driving, I had gone 200 miles at the half tank mark, but only 240 at the three quarter point! That's a huge error - more than a two to one difference in miles per quarter tank.
I try not to go much below a quarter tank, but it just seems to drop even faster after that. Horribly non-linear, and just adds to the pain of having a fairly small tank and a MPG readout which reads almost 10% higher than it actually is.
These errors are much worse than any other car I've ever owned. Surprising and disappointing for a tech-heavy car. I would expect much better accuracy than this.

 

[Beefer]

YES!!! Annoying as F.

I’ve learned to live with it. When I hit 1/4 tank...I know I have to fill up within 2 miles...LOL

If I’m at 1/4 tank...I can floor it in Sport to the nearest gas station and be on E...LOLOLLL.

 

[Husky]

Exactly. Once I hit a quarter tank, I treat it as almost empty. You can practically watch the needle drop at that point if you're in Sport mode.

 

[Julius88]

LOL...I thought it was just my gas gauge that was doing this. 1/4 tank is basically time to fill up for me as well. On a related note, the gas mileage is killing me. Since I'm still working remotely, 90% of my trips is city driving and I'm averaging less than 18 mpg, and it's not like I'm a leadfoot or anything (at least I don't think I am). It's gotten to the point that I keep it in ECO all the time. Wish there was a dedicated sport button on the steering wheel to quickly put it in sport mode for those times I need to accelerate quickly.

 

[EdP]

LOL...I thought it was just my gas gauge that was doing this. 1/4 tank is basically time to fill up for me as well. On a related note, the gas mileage is killing me. Since I'm still working remotely, 90% of my trips is city driving and I'm averaging less than 18 mpg, and it's not like I'm a leadfoot or anything (at least I don't think I am). It's gotten to the point that I keep it in ECO all the time. Wish there was a dedicated sport button on the steering wheel to quickly put it in sport mode for those times I need to accelerate quickly.

Short trips are a killer on MPG. Probably not much different in the other modes as a cold engine runs rich no matter. I solved the problem by not looking any more.

 

[aweetod]

LOL...I thought it was just my gas gauge that was doing this. 1/4 tank is basically time to fill up for me as well. On a related note, the gas mileage is killing me. Since I'm still working remotely, 90% of my trips is city driving and I'm averaging less than 18 mpg, and it's not like I'm a leadfoot or anything (at least I don't think I am). It's gotten to the point that I keep it in ECO all the time. Wish there was a dedicated sport button on the steering wheel to quickly put it in sport mode for those times I need to accelerate quickly.

Havent tried smart mode before but that sounds like exactly what it is was designed for

 

[PJ Genesis]

On my 2.0T AWD, at the 1/3 tank level, the gauge seems to hang there for a bit. Sometimes showing a higher level of fuel. A bit strange. Just filled up from an 1/8 of a tank, and it took on just under 13 gallons. So I know there is some gas there as it approached E.

 

[Julius88]

Havent tried smart mode before but that sounds like exactly what it is was designed for

Maybe...I might be alone in this but I don't really trust Smart mode to do what I want (I can honestly say I've never once put it in Smart mode). Rather than hoping that Smart mode can guess what I want, I'd rather have the ability to just tell the car what to do with a push of a button.

 

[joegr]

... I don't really trust Smart mode to do what I want...

It could be worse. I think that Tesla is rolling out a feature where the car guesses if you want to go forward or reverse, instead of just having a shifter.

 

[csu87]

most car manufacturers have a non linear fuel gauge. sometimes its the opposite, fast from full to half, slow from half to empty, so that you dont run out of fuel unexpectedly (my dodge does this), some its full to half slowly and half to empty faster to give you the impression you are getting better mpgs (my bmw and g70 do this). I think the only car ive had that is pretty linear is my 94 trans am.

also has to do with how it reads fuel. some use floats that dont float all the way to the top so it reads full even when its not and some use sensors to give a more accurate reading. but even with sensors, there are deadbands. And then shape of fuel tank adds another complexity to it. some have a narrower base so the level of fuel is the same, but the amount is different

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[Husky]

Not sure how non-linearity keeps me from running out of fuel (especially if a warning light comes on in either case).
As far as the mpg goes, it seems like I'll feel like I'm getting good or not-so-good mileage either way, just depends on whether it's during the first half a tank or the second half a tank. Unless you always full up at the indicated half tank mark I suppose, but that's like every 160 miles, which is a nuisance. Plus, once you've filled it up and done the math, it doesn't really matter what "illusion" the gauge creates, you know the truth, haha.

 

[Husky]

As far as the shape of the tank goes, I expect that can/is taken care of by the computer, which can easily have a correcting algorithm to linearize it. I could be wrong, but I doubt it's like the old days where the sensor in the tank was connected directly to the fuel gauge.

 

[csu87]

Not sure how non-linearity keeps me from running out of fuel (especially if a warning light comes on in either case).
As far as the mpg goes, it seems like I'll feel like I'm getting good or not-so-good mileage either way, just depends on whether it's during the first half a tank or the second half a tank. Unless you always full up at the indicated half tank mark I suppose, but that's like every 160 miles, which is a nuisance. Plus, once you've filled it up and done the math, it doesn't really matter what "illusion" the gauge creates, you know the truth, haha.

if it tells you there is 1/8 of a tank but really there is more than an 1/8th, you dont get the unexpected empty fuel tank. gives you more time to figure out your gas situation. granted, for a lot of people it doesnt matter because they know how far they can go with an 1/8 of a tank and base it off that.

as for mpg, its just an illusion. some people think "o i can go XXX amount of miles on a half tank so im getting great gas mileage". again though, for a lot of people, its nothing more than an illusion because they calculate their gas mileage when they fill up.

As far as the shape of the tank goes, I expect that can/is taken care of by the computer, which can easily have a correcting algorithm to linearize it. I could be wrong, but I doubt it's like the old days where the sensor in the tank was connected directly to the fuel gauge.

as far as computer aided correction for the reading, sure that can be done, but its not something that really matters so why "fix" something that doesnt matter. just adds another layer of complexity that isnt needed.

 

[Husky]

Speaking as an engineer, it sounds like you're talking about on offset in the gauge reading, rather than a non-linearity in the scale factor. It would certainly be bad if the tank was actually empty when reading 1/8, but that's not what we're talking about.

With the crazy shape of today's fuel tanks, to maximize the use of available space, I suspect it's already being fixed by the computer. Just a few lines of code, or a simple look-up table in software to linearize the reading. Nothing complicated. It's not like the 60s, where the tanks were mostly just rectangular.