Quick note: FYI - My 2024 TX 500h (fall of 2023 delivery) with 63,000 miles only takes about 12 gallons max and normally 10 to 11 gallons. Milage was up to 25 MPG when I was doing 60 mile commutes mostly on a turnpike and weekend trips of 200 miles. Last three months with a change in my career I have almost driven entirely local including slow speeds with rush hour traffic on local roads. my milage dropped to 22 but has stayed in that area. I will check with the dealer on the TSB. I have found them recently to be short of technicians with appointments as much as 6 weeks out. The service staff seem to avoid any non-routine issues.

 

Hmmm... Well .. I just filled up my 2026 TX 500h and DID experiment by topping it off a bit beyond the slow-fill 2nd click-off. It easily took 16.8 gallons rather than the usual 16-16.2 gallons. More than I expected. Still, no fuel spilled out, none was visible in the filler neck and the car was and is running normally. I wasn't about to try and fill it up to the very top.

Note that the LOW FUEL light had come on just 4 miles earlier and range had just gone to zero (REFUEL NOW).

BTW - the Toyota Grand Highlander TSB on this issue is: T-SB 0060-25. Don't know what the equivalent one would be for the Lexus TX.

 

I have had an ongoing discussion with Lexus about the fuel capacity for over 1 1/2 years. Our 2024 TX 500h was diagnosed by a Lexus Field Tech Specialist with a deformation of the fuel tank. The solution on the service invoice stated that a redesigned fuel tank would be the solution. Lexus is very aware of the inability to fill the fuel tank near capacity. An owner of the car should not be trying to figure out how to get more gas in the tank. This is false advertising or fraud to lead the consumer (owner of the car) to believe the mileage range would be much greater than it really is. Our 2024 Lexus TX 500h holds only 13 gallons of gas when the fuel gauge reads close to empty. We are not going to run it past zero DTE miles because of warranty and peace of mind. The issue needs to be fixed. We have waited for a solution for over a year. I have notified Lexus corporate (Executive Lexus Engagement Center as well as letters to the president and vice president of Toyota) numerous times and it has made no difference. i am now in the process of contacting the attorney general of our state to make a formal complaint. The real mileage range of this car needs to be advertised and clearly stated when purchasing the car. Good luck with your fuel capacity issue. Hopefully, Lexus will understand how frustrated their customers are and get a fix for the problem. I have read the words "class action lawsuit" when doing searches about the fuel capacity issue. A fix would be a much better solution for everyone involved.

 

Hmmm ... we're either driving completely different model cars, you're not refueling your TX500h properly, the car has had a significant modification to the fuel system between 2024 and 2026 models (I'm aware of ONE LIKELY TSB related firmware update of the fuel level reporting system) or your fuel system suffered significant damage from some cause, either design related or otherwise. All of these are possibilities and I'm NOT the arbiter of which case, alone or in combination, is which. I know what I'm seeing in my own 2026 TX 500h, though.

I'd read posts about fuel tank issues BEFORE purchasing my TX500h and it REALLY caused me to think twice about buying the vehicle. I was VERY concerned then happily surprised when I had no such issue with fuel tank capacity - or any other issue for that matter. The car easily fills to 16-16.2 gallons using the SAE recommended filling procedure that was originally used to rate the tank (auto fast fill follows by 1-2 auto slow fills on level ground). That's pretty much how I've done it on ALL of the MANY cars I've owned over decades. None has ever suffered any damage. Nor has their warranty ever been voided or threatened to be voided because of this.

I recently and very carefully tried filling the tank even further to see if it was even close to topping off (obvious fuel in filler neck gas fumes, etc.). It wasn't - instead it took another 0.6 gallons and probably could have gone further - but I don't like to see ANY gas standing in the filler neck and so just stopped. The Costco pump indicated 16.8 premium gallons put in against a tank rated at 17.2 usable gallons. In my book (my opinion only for my specific 2026 Lexus TX 500h) the easily usable capacity of the fuel tank, not including an unknown but LIKELY 1 to 1.2 gallons of likely usable reserve, is 16 to 16.2 gallons. Which seems to give me a reliable (flat) highway range of about 400 miles (or a little more) at 25 MPG. Less when climbing or on hilly terrain. That's about the same as my old Gen II 5.7L V8 Sequoia, much better then several of my cars and just a little worse that my wife's 2023 Lexus RX350. So I'm happy.

BTW - in every case where I've run the car down to REFUEL NOW it has not sputtered, hesitated or complained in any way, Including when running on hilly terrain. And the fuel filler hatch pops open immediately when I press the release button. So - due to my personal experience with the 2026 TX 500h so far, I have little personal concern about running the fuel level down to indicated REFUEL NOW especially as the SAE standard clearly indicates a usable reserve usually exists below this and my own experience shows that there is a reserve (no fuel starvation). I do NOT plan to run the car beyound that point - a reserve is for ... reserve ... typically unknowns ... like an unexpectedly closed gas station. And on long trips far from home, I usually refuel at 1/4 tank (or more) just to be safe against even bigger unknowns.

It is what it is. This is how I drive and refuel my own Lexus TX 500h Performance Luxury and this is what I've seen. So far, no unpleasent surprises.

I have no experience with YOUR TX 500h and my only comment is that If I had the problem you're describing (significanly damaged fuel system - collapsed fuel tank) I'd have it fixed immediately, by an independent repair house if necessary - THEN I'd take the results to Lexus and the courts if necessary. Because I consider ANY fuel system damage dangerous (been there, done that - 1988 Nissan Maxima - famous EFI leaks/fires, Nissan Z car with damaged fuel tank that LEAKED - bottom puncture) and feel that driving around in a vehicle that could pose a risk to others is just irresponsible.

 

This is the difference between you two. TCLexus believes or doesn’t want to try to drive until the DTE displays refuel in fear of running out of gas or damaging components like fuel pump. Lots of owners have tested Lexus/Toyota DTE accuracy. Close family member drives a 2024 TX 350 and I haven’t informed them of the inaccurate/conservative DTE so they believe the DTE is accurate and drive, refill, repeat. I’m sure they don’t know how big their fuel tank is.

Unless Lexus provides a software update to their DTE you have to learn to deal with the 12-13 gallon fill ups or keep driving until refuel is displayed.

 

Oddly enough the fuel gauge in my TX 500h also seems to work fine as does the "LOW FUEL" indicator, which I've found seems to operate independently of the DTE estimate and gauge. And I've measured and figured out the non-linearity of the gauge, which is usually different in every car model, in my experience. SOP for most old timers, I think. Changing driving terrain and conditions always impacts DTE, so I take the car's estimate as an interesting number, but trust the fuel gauge, the LOW FUEL light and my instincts. So far, the gauge reads "REFUEL NOW" about four to seven miles after the LOW FUEL light goes on. And the LOW FUEL light IS sensitive to the slope the car is on. And there is a reserve remaining after empty.

No different than on any of my other cars.

In the end, I have no problem cruising 300+ miles with the car, on the highway or in city driving, on a single fill-up. And I know I can go much further on the highway if I need to.

THAT's what I REALLY care about. RANGE (Vegas and my friends are about 300 miles away - a regular run for me - and no, I don't generally gamble).

 

I never let the low fuel light turn on.....

 

Nothing wrong with that - it's all about your comfort level and reserve against need to refuel.

That said, manufacturers stated tank capacity is generally TOTAL USABLE CAPACITY, meaning everything down to "EMPTY" as indicated on the gas gauge, LOW FUEL light ON, DTE showing zero or "REFUEL NOW", plus some reserve beyond that point. The Society of Automotive Engineers maintains standard SAE J398-201211 which explains pretty well how fuel tanks are generally rated for capacity (no guarantee that ALL makers follow this standard - but it looks to me like Lexus/Toyota PROBABLY does).

From my experience with my own 2026 (November 2025) TX 500h, the reserve seems to be about: (calculate this) 17.2 gallons (user manual stated fuel capacity) -16 to 16.2 gallons (how much I usually put in via "fast fill, sow fill, slow fill" - see SAE J398) = (about) 1 to 1.2 usable gallons (on a level road).

I'm not too worried about the fuel pump or EVAP system, either. I can SEE the EVAP port in the filler neck and fuel never seems to be anywhere near it after I fill up, and I've never had a fuel pump failure caused by this method of filling the tank (i.e. low fuel) in ANY of my many vehicles. And I'm NOT a teenager.

Around home, there are multiple gas stations just a few blocks away, including a Costco. So there is little risk I'll run out of fuel when running down to indicated EMPTY. On long trips I generally refuel at 1/4 tank indicated to allow for unknown unknowns. For me this means about 400 miles of safe highway range in the TX 500h, unless I'm in the mountains, but 300 PRACTICAL miles to refuel to stay in my own "comfort zone" on long trips.

It's pretty hard to blame the manufacturer of a car for incorrectly rated or too little fuel tank capacity if you've never actually tried to use most of the fuel in the tank or have never really filled it up, due to various anxieties. And DTE algorithms only provide rough "guesstimates" based on tank state of fill, past driving habits, terrain and weather conditions. They've never been precisely accurate on ANY of my cars - Lexus, Toyota, Honda, Ford, Chevy, Lotus, BMW, etc. They CAN'T tell what future driving will bring - but only extrapolate in very simple ways from what has been - with a little margin thrown in (Engineers LOVE margin - keeps us out of trouble). DTE does not account for fuel changes (summer to winter blends), climbing mountains (unless you live in them), speed, driving mix changes, etc. So the fuel gauge and LOW FUEL indicator are always my main references.

I'm an engineer and grew up working on my own cars and those of others. I understand design margins and reliability. And I've characterized my 2026 TX 500h Performance Luxury fuel tank pretty well. Yep - a spreadsheet with fill up, gas gauge data and mileage/MPG, annotated SAE J398-201211 diagrams showing probable capacity above FULL, 4/4, 3/4, 1/2, 1/4 and EMPTY probable reserve, test runs through the hills, flates, city, highway etc. I'm pretty compulsive that way. (And my wife STILL loves me! Amazing!) Fuel economy is still changing (improving - car has only 1,200 miles on it and is not yet "broken in"). So - this drives how I manage fueling MY vehicle.

What you do is up to you, and only YOU can decide what is appropriate for YOU and YOUR vehicle, and only YOU bear the responsibility. So by all means, stay within what YOU feel are "safe margins", whether ot not anyone else feel they are too conservative. I respect that.

These are just my own personal opinions.