Nope, it's 12. Owned it for nearly ten months now and ran it till practically empty and it's definitely 12. Unless there's a 5gal cinder block in there causing me to both get horrible gas mileage and blocking the capacity of tank too!

 

You are definitely wrong based on the manual on page 564



Manual

 

Thanks. I was going to post the same capture from the manual.
12Gal tank is definitely wrong. I know Lexus has ~3gal reserve when the low fuel warning comes on. When I pump this to full, it's usually 14.5gal making the fuel tank ~17Gal as spec.
The only smaller fuel tank on RX that I know is the RX450H+ of 14.5gal but it also has ~37miles of EV range and rated about 35MPG.

I'm considering moving into the 5th gen RX but I'm on watching on the sideline as to which trim level I should get. 500H or 450H+.

 

Speaking from my experience not what's in the manual. My max capacity at empty with the needle on E and the light on, less than 0 miles to empty on the dashboard (not counting whatever reserve there is) is 12 gallons. I've owned it since new and nearly ten months, 8k miles now. I think I ran it one time past zero miles till empty and it just had a dash on the screen and was actually below E and it was 12.1 gallons. I can take a picture next time I'm at the pump to show you. For all of you that have this vehicle, how many total gallons can you put in your tank when it's empty and what's your miles to empty when you fill up? Mine is 330ish and 12 gallons. Could it be they put the wrong size gas tank in my vehicle at the factory? LOL. I'm also getting 19mpg vs the 27-28 I'm supposed to. I've owned Lexus vehicles since 1996 and dozens upon dozens Rx as well as hybrids from the 400h to 450h to ES as a dealer myself when I owned my business. Never seen anything like this. Not a newbie, by any means. Certainly still learning every day, but I'm telling you MY experience in MY vehicle, not what the manual says. Real world. Let's hear your real world experience as well. Trying to understand if I have a lemon or not/anomaly situation. Historically Lexus gas tanks have on average two reserve gallons so the fuel pump doesn't overheat sucking air when you go around a corner. Even with three gallons reserve, I'm not experiencing the proper fill up with my vehicle's tank...unless you all are experiencing the same? Thank you.

 

It's highly unlikely that Lexus put the wrong fuel tank in. Much more likely, based on my experience running the RX450h+ completely out of gas, is that Lexus has grossly understated the reserve.

 

There are lots of posts about the tank capacity. I always put between 12-13 gallons in after the light comes on. No one including Lexus can explain where the other 5 gallons is. Some of it is obviously a reserve. I usually get around 36 MPG in my 350h so that gives me over 400 miles between fill ups. I have decided it's a waste of time trying to figure out whats going on with this crazy tank. Just drive and enjoy.

 

I know exactly where the extra fuel is in the RX450h+ It's below the useful range of the fuel level sender.

 

The 450h+ has a smaller tank than the 350h. My tank holds 17.2Gal. If I can only get the use out of 12 gallons in the tank, those other 5 gallons that I'm carrying around do me no good mile wise. 5 Gal x 36 MPG is 180miles. Fuel level sender, reserve or what ever mean nothing to my range. Again, I'm driving my 400+miles, watching the light go on, filling up and repeat.

 

That's your choice. Most will probably do the same. I will do the same most of the time, but now I know I have a larger reserve than Lexus claims.

 

So I just got my fiance a new Grand Cherokee 4xe and it has the exact opposite problem.

When the range shows 30 miles, the car runs out of gas and battery within 5 miles and leaves you stranded. I guess its all about perspective with the 500H haha. At least Lexus gives us 150 miles to find a gas station.

 

Well, that’s 5 gallons of fuel you’re always carrying. I hope they fix this. The light should come on at 14gal used up leaving you with 3gals. With 30something mpg, if you can’t find a gas station within 100miles, move somewhere else.

 

I'll be shocked if Lexus fixes it. Best I'd ever hope for would be a TSB stating that it's normal to have a 4 or 5 gallon reserve, and/or maybe an update to the manual.

 

I agree WellsB. Lexus might make some changes in future vehicles but no way they are going to fix this. I believe that the fuel sensor is physically not reading the tank correctly due to an engineering error.

 

The only way I can sneak in 14 gallons is by driving this thing until its running on fumes.

However, I can force 14 gallons by slow pumping after the first 12.

Its 100% a sensor issue

 

Be careful, it's not worth getting gas in that evap canister. Best to quit after the 12 gallon click off.