Range - How Much Gas is "Usable"

[Clark2262]

I drive a lot of miles and a priority when choosing a new vehicle is range - the combination of fuel economy and size of gas tank.

I'm doing very well on fuel economy. I drive in "Eco" mode all of the time averaging over 18mpg.

However, if I run until I have 8 miles to empty, the most gas it will take is just shy of 17 gallons in what should be a 21 gallon tank. I'm not able to use just over 4 gallons.

This is just not acceptable. I'm having to stop for gas every three days at the most and some times every second day. I should be getting over 400 miles to a tank and not just 320.

My last SUV with same tank would get me almost 500 miles between fill-ups. It had more horsepower but less towing capacity. I did not expect 500 miles but I do expect to be able to use all of the gas in the tank. (Last SUV had 40 more horsepower and weighed about 600 pounds less than Lexus.)

Anybody else having this problem?

Clark2262

 

[nonamex]

Toyota/Lexus have been very conservative in the reserved gas arena. You would need to run it bone dry to get the full 21 gal. For reference, I drive in Normal mode and my range is 297 mi.

However, my vehicle is loaded with roof rack, light bar, rtt, dometic cooler, and lots of gear. Getting 297 mi is a win in my book. I would love to get 400 mi but that won't be happening any time soon.

 

[JoeRob]

Is there a 4 gallon fuel reserve in a 21 gallon tank? Am I hearing someone say that the vehicle mileage and distance is calculated on 17 gals and not the full 21.1 gallons????
I drive in Normal and when possible, I drive with A/C OFF, windows cracked for some air flow. Out on the interstate, I will run A/C in auto. I turn all the CLIMATE switches OFF.
My GX has about 1500 miles and consistently shows fuel mileage at 17 around town, 17.4 highway running interstate at 70 - 75 mph.
When I fill up the tank, the miles to go indicates about 292 miles. When the fuel nozzle kicks off the pump indicates 17. 1 - .3 or .4 gals.

 

[Clark2262]

I'm actually getting over 20mpg now with almost 10k on the odometer. I'm driving pretty conservatively and always in "Eco" mode. It's still now what I expected at all.

 

[munkeeboi]

@Clark2262 I see you have a premium +. I initially felt good about my car computer calculated mileage, but started using gps and speed traps to see that that the speedometer (and odometer) was several mph faster than I was actually going.

This got me thinking that that Speedometer was not calibrated correctly on the premium models 20" wheel. The Premium 265/55/20 (31.5') are about 1" smaller in diameter than the Stock OT 265/70/18 (32.6") and Luxury 22's (32.4"). My hunch is that all GX's are calibrated to the OT 32.6" wheel, thus creating a false reading on the premium with the smaller diameter tires. Using Tire Size Comparison it estimates a 2.5 mph difference between OT and premium tires at 70 mph, which is roughly the difference i was seeing on my GPS and speed trap speed.

I have since switched to 33" tires and my speed is just a tad bit lower than my indicated speed on the speedometer, which is to be expected.

The bad part about this are two fold...false sense of MPG and even worse, your miles will rack up faster on the odometer. This sucks for a lease and for resale down the road.

TLDR point is ....get bigger tires, the mileage already sucks, but at least you won't be lying to yourself

and to stay on topic, for me....it appears that on a full tank the car calculates your mileage based on 17 gallons, but as it nears empty, the range appears to go down more slowly. anyone else observe this? I seem to go further on that last quarter of the tank than the first quarter of the tank

 

[JoeRob]

ok........ I think we are way over thinking this gas mileage thing. I going to forgidaboutit and start filling up at 50 miles remaining. Costco is just a half mile away...

 

[jclaffee]

ok........ I think we are way over thinking this gas mileage thing. I going to forgidaboutit and start filling up at 50 miles remaining. Costco is just a half mile away...

Agreed. Your comment made me chuckle 'cause nearest Costo for me is 3+ hours away (next to the nearest Lexus dealer)!

 

[IARob]

I have run past the 0 mark on my Premium Plus knowing there are roughly 4 gallons remaining. My biggest question is whether Lexus is over zealous for their reserve or is the pump exposed somewhat when you get past that 17 gallons of consumption. To me, that is crazy to think they designed it this way but I certainly don't want to burn anything out. On a side note, I do a lot of highway driving going to tournaments on the weekends and get roughly 20-21 MPG with no A/C on here in the Midwest this time of year.

 

[GX470-550OT+]

Other thing to consider is---does Lexus require the 4 gal of gas to help cool the fuel pump from overheating and easier to make customers think they are empty when not in order to keep this volume?

 

[AtomicEric]

From a prior post I did. Still see true.

1. Milage Until Empty​

   So the digital range formula sees to be: Display Range "Miles" after fill up = (21 gallons - (60 miles of reserve / current "avg." MPG)) / current avg. MPG So despite anyone's avg mpg it seems we all should have about 60 miles of reserve fuel. Be it 3, 4, 5 or 6 gallons in reserve.
   • AtomicEric
   • Post #21
   • Nov 28, 2024
   • Forum: Lexus GX Talk

 

[DJ’s Sled]

FWIW: I discovered one thing yesterday I wasn’t aware of. I filled the tank (it showed 31 miles remaining) with the slower refill notch on the gas handle. It came to 16.07 gals. Didn’t seem quite right, so I manually, slowly added about a half-gallon more…and didn’t hear or see any foaming or indicators on the filler neck that it was actually full yet. So did that again..and ended up with a total of 17.370 gals.
I never had this issue on my other or recent vehicles (having tested them same way), so I never bothered adding additional to them.
Outside temp was about 70 degrees.
I’m going to carefully try this the next few times at random gas stations and see if it happens routinely for me.

 

[AtomicEric]

Interesting observation. If needing to max the range out that may be something to consider. Not sure I would do on a regular basis but if road tripping and putting down miles right after fill up that may help. Will gbe interesting to know your findings.

 

[DJ’s Sled]

Between each of those manual, slowly ‘add more’ tests..I only waited like 8 or 10 seconds. I was really surprised and a bit confused why it happened. Maybe just that particular pump. I plan to find out.

 

[Mucksavage]

I love my GX OT+ but I am getting 14.2 mpg blended. I drive on the highway about 30% of the time. I do have a CBI roof rack installed but everything else is standard.

I do not drive in ECO mode or restrict using the AC. I don't feel like I should have to compromise.

I might be moving to another vehicle. My 2016 4runner TRD Pro has everything modified including a roof rack, bigger tires, etc and I get over 16 on average.