UniSlayEX

I bought an '08 350 in December with 12.7k haha so I believe it.

TooFly4Ya

Sounds like your ECU is calculating your Miles Until Empty wrong. I would google maps my commute in miles, Fill up the tank then see how many times I traveled my commute until the light came on. For me light comes on around 25-50 miles left. From what I can remember usually dont let it get past half a tank.

whitebeast

iTrader: (5)

If you're REDLINE (high RPM) your IS350 MOST THE TIME, you have 180 miles to the tank (it's normal)
But in this case, 180 miles to the tank is not right at all

01ES300NYC

iTrader: (2)

^^^^ yup i avg 180-190 per tank ......but i only avg 12mpg..... nothing wrong with my 350 tho. i can get almost 30 highway on long trips... i just drive aggressively most of the time n push my rpms....lol some mornings it takes me 7mins to get to work. i live 12 miles from my job 75/hwy 25city

ifx

I reset the ODO after i fill up. The fuel sign comes up at around 185 miles.. Is this not accurate?

UniSlayEX

You should be at about half a tank IMO.

Try the battery reset and see what comes of it. Like others have said, run it to empty and calculate how far you have actually gone.

The electronic counter isn't the most accurate but it gives you a good read-out. Mine is fairly accurate FYI.

Gville350

iTrader: (10)

Perhaps the floater in the fuel tank is no good?

neilr11

Avg 24 mpg in my 08 350, I do not drive it hard.

Toymota

Could be a problem filling your tank? Because 180 miles does not match your indicated 21mpg. Actually there are two displays. The one that says AVG is the lifetime average so it adapts very slowly to changes. So you should use the TANK AVG. Maybe the pump clicks off too soon so you're not filling it all the way? How many gallons do you put in? Should be around 14-15 gallons. 180 miles on 14 gallons is actually only 12.9mpg.

Or maybe there is a sensor problem so the car stays in open-loop all the time? This is normally just the warm-up mode and extra fuel is injected to keep the engine running smoothly, but this also trashes your mileage. Also if you make short trips with lots of cold starts, or let your car idle to warm up (idling is much slower than driving to warm up the car), your car spends more time in this warm-up mode and your mileage will be trashed.

nielsio

Just filled up the tank of my 06 is350. Needed to re-fill 3 quarters which then listed 237 miles, so at 180 ur definitely off. However if i hear you guys getting 300+ sounds like i'm a bit off too

ISFWes

The fuel display on mine is not that accurate. To get your real mileage.

Fill up the tank to the top.

Reset the trip odometer to zero.

Drive normally till your empty warning light comes on.

Refill your tank.

Divide miles by the number of gallons you just put in.

This will give the real total of your MPG.

The tank holds 17.1. So say your light comes on at 2 gallons left. If you drove 300 miles and put 15 gallons in. There is your 20 MPG.

You may a problem with the gas tank sending unit. Or the ECU.

ifx

Thanks for all the replies guys. I think i may have figured it out. It seems to be an error on my part.

I wasn't putting premium. LOL. As of last fill-up, I filled to about 3/4's and I've already gotten 190 miles now, with still a quarter tank remaining.

Bought the car as a beater, and also didn't really think the 250 needed premium. Oh well, now i know. Car will be up for sale soon. 06 now with 13k miles, completely bone stock, recently serviced in January at Lexus Of Palm Beach. Car is pearl white. if anyone is interested, shoot me a text at 954-235-3177. Trevor. Thanks again guys!

And btw the car has a clean carfax, and NO paintwork. I'am the 2nd owner as of about 3 months ago.

And i'd like to clarify, the car is NOT beater material (as in messed up etc.) The car is immaculate in and out, and even smells brand new. I kid you not.
I say "beater" because I've been using it daily.

anthrax144

Yup, your windows may not work properly after unplugging the batter. Plug it back in and then roll each window down and up individually using their separate controls (not the one on the drivers side.)

Also, how many gallons of gas are you filling up with? We have a 17 gallon tank (or something close to that.) If you are only getting 180 miles but 21 mpg, it sounds like you're only filling up with 8 or 9 gallons. Although my drive is pretty even city and highway, I've never averaged less than 21.5 mpg. I usually get about 350-370 miles and fill up with 15 gallons.