Fuel Gauge Accuracy, Reserve Amount?
 

New 2014 Z owner (2 weeks and loving it!) Long story short, I drove until the gauge read 20 miles till empty, then it changed to flashing --- which worried me as I still had about 30 minutes to home. When I filled up the tank only took 16.6 gallons leaving 2.4 gallons in reserve.

This doesn't really concern me but it is useful to know exactly how much further I could have driven if I were in a situation that demanded it. Is this a typical quantity to have left in reserve after the gauge begins to flash --- ?

I think it depends on the driving condition that you are going through. is it stop and go, hwy, etc. i try not to let it get to that stage, but if you do, when the light comes on i believe there should be 2 gallons left. they say the bad gas settles to the bottom so when you let it go to reserve it's pulls everything that settled to the bottom... anyways that's what i've been told and what i go by lol.

i'm sure someone will have a way better answer for you :)

My experience indicates it is an estimate based on your recent driving habits. If you were driving spiritedly, it will calculate remaining miles based on that type of driving. If you were driving on the highway, then it will calculate based on that. I've had it say 45 miles left, and then made a couple of redline pulls, and less than a mile later its flashing "---"

I have put 50 miles on the car after it started flashing ---. I think I filled up with ~18.5 gallons (19.1 US Gal capacity). But I pay close attention to the miles I can get on a tank with different driving habits. I base my fill ups on how many miles I have on the tank and how I've been driving the car, not anything the car tells me. I think you're probably right that it leaves you about 2.5 Gal or so when it starts flashing --- (can't be exactly sure though).

Thanks for the reply. :tiphat: I understand mileage will vary depending on driving style which is why I'm more interested in precisely how much fuel is left in the tank when the gauge reaches E. The manual says "the gauge indicates an approximate fuel level in the tank" and "There will be a small reserve in the tank when the fuel gauge reaches E".

I'm just curious if a 2.5 gallon reserve is typical for the newer Zs so I know what I have to work with.

I think you're pretty close - I doubt it's changed much through the years. And honestly, that's probably good enough for your needs. If you want to run it closer to empty, fill up a gas can and take it with you for a drive until you run out of gas. Just make sure you pay attention to all the variables, so you know what to expect down the road. If you want to be thorough, do it a few times to calculate a more accurate average.

The dot gauge is notoriously inaccurate on the older models. I haven't seen a lot of complaints about it in the newer models (it seems fine on my 2011). If you want to know exactly how much fuel is left in the tank when it reaches E, fill up as soon as you can after reaching E. Then you will know the exact number for your car.

Somewhere around 2-2.5 gallons seems right. I don't usually let it get to the point of flashing "---", but, the few times I have it, took about 16 gallons to fill 'er up.

;) LOL I don't think that's going to be necessary, I'm just trying to learn the details of the car. I'm the curious type that's always asking questions...

Thanks!, That's what I'm looking for.

My gas backlight display flashes when it reaches approx below 50 miles to empty. Then the figure varies depending on driving, one moment it could say I have 35 miles left then a few seconds later I have 49 miles til empty. I drive very light footed when it reaches the E flashing scenario.

The estimated range and fuel gauge are very inaccurate. Had about 2.5 gallons left when I got the "---".
When I look at the fuel gauge:
1/2 = 2/5
1/4 = 1/4
1 dot = 2 gallons
Anything under 1/4 and don't take long right hand turns at speed.
The estimated range is very inaccurate and probably should never be used.

Same here. So far that seems to be the norm.

I can't wait to try this to confirm. Please define "at speed". Are we talking 60 mph or 140 mph? I assume with high G forces...

If you look at the shape of the gas tank, there is a large hump in the middle of it. It is indeed g-forces that cause the gas to slosh over the hump to the side without a fuel pickup. The fuel starvation issue seems to occur when there is a combination of g-forces and lots of throttle around a long right hand curve. With regard to speed, it's more about the individual curve; different curves are going to see different speeds. I wouldn't be surprised if someone were able to induce fuel starvation by doing donuts in a parking lot.

Basically, try a long right hand curve as fast as the Z can take it at high RPMs with very little gas. This is your best chance to induce fuel starvation :ugh2:

I've induced fuel starve on a sharp right hand turn at a traffic light. It wasn't until I was a mile down the road before I felt it stutter. The second time, same scenario, but I parked it. When I went to turn it back on, it didn't have enough fuel in the lines to keep it going.

Its been widely reported that the gauge is often not all that accurate on the 370Z and often times you have quite a bit more than it says. That being said its actually way way worse on my GT-R. I have had the DTE go down to 0 (and gas light on) and filled up and only put 12 gallons in! Its got a bigger tank than the 370Z being at 19.5 gallons. The issue is *much* worse on the GT-R. I would say 1.5-2 gallons is typical to have in the reserve when DTE goes to -- on the 370z.

This is definitely an issue on the 370z. I Have had fuel starvation all the way up to a half a tank of gas. It will recover if it has that much gas in it but it almost screwed me once as it stopped accelerating for a few seconds while I was trying to merge and the lane was disappearing.

I have had it not recover several times if I am under 1/4 tank of gas but I generally take the turns way softer due to the times I have been stranded due to this issue (happened 3 or 4 times now).

370z fuel tank is 19 gallons so the GT-R is only .5 bigger.
Honestly the fuel tank takes into a lot of factors but it is terrible all around. I can sit in the top 2-3 dots for a few days and then in the next 24 hours be well below half a tank with the same driving.

My first encounter with the estimated fuel gauge involved the little lady demanding to know why I took her out on a country road without a proper fuel load. As the gauge kept spelling out how many miles were left 50 miles then a mile later 41 miles then another mile 29 left. It fell right off then went to bars. The entire time I'm being ridiculed. When we got to town and found gas I too only took about 17 gallons as well.

Fuel starvation is more likely to occur down at the dregs.

I use my car to drive 130 miles round trip daily. I get the flashing light each tank at 450 miles and almost always put in 16.5 gallons per fill up(3 times every two weeks). this leaves 2.5 gallons in reserve. I average 27.2 mpg. I love commuting in this car.

Good info. Thanks for all the replies!

BTW it's a shame ATL doesn't build a replacement tank that solves the problem, even if it held less. At 2k, you'd have to really want one - bad...

The lowest my dots got was half way between 1/4 and 1/2. I have never gotten below a 1/4 of a tank. I like to keep my Z filled up.

:icon18:

I'm envious of your mileage. I just hit 30,k after owning the Z for 14 months. My personal best has been during a long highway sprint when one fill came in at 25.3, generally averaging in the low 24 range. (MPH could be a factor :icon17:)

As for the actual OP thread topic I've never been able to get in more than 16 3/4 gallons at a stop. Something between common sense and fear make me fill when the bars blink for very long. Those last three dots are a bad joke.

how are you averaging 27.2???

So at 1 dot remaining, it takes around 16.5 gallons to fill.

Do we really have 2.5 gallons reserve?

I'd imagine we have 1 or 2 gallons that are unusabe by the pump. Any thoughts?

Probably low RPM's and flat roads with few stops and high speed limits.

And not very :driving:

Gas Gauge
 

My new 2014 definitely reads different than my 2012. The '12, I could go 70 miles before the lighted gauge started dropping. The '14, it starts dropping much sooner, like 40 miles. The first mileage check was 26 mpg, the second was 22 mpg highway. Really got me concerned. This is with mild driving, still in the break in period. ??? 500 miles.
Chuck

Hmmm. That mileage does not sound so good. Are you basing this on what the computer says or my comparing actual gallons and miles?

i try to keep my rpms 2-3k range but then again seems every time i get a chance to step on it a little bit i take advantage of it :happydance:

Below a half tank it's all about how you drive your Z. Doughnuts to the left are fine, doughnuts to the right are a problem.

:icon18: Awesome.

Mines the other way around, it goes higher after the initial alert of the amber light business. Then of course it goes lower after time.