Have you lifted it up and spun the tires to see if there’s any resistance? Could be dragging brake, bad wheel bearing, or engine related. Anything causing drag on the drivetrain/wheels will reduce MPGs like that.

 

We have been hittd with snow storm. We got 30 cm of snow so i cant lift any wheel. Wouldnt a bad bearing or seized caliper piston make any sound/noise or symptom?

 

Not in all cases. I’ve read about many that never heard anything.

Also remember you’ll see close to a 5 mpg drop in snow (more or less depending on your situation).

 

Some questions:

Have you cleaned the MAF?

Have you cleaned your fuel injectors?

Where do you buy your gas?

Have you replaced your oxygen sensors?

You say your mileage is 100% city. What kind of mileage/usage do you actually have? (ie., start your Lexus up cold, drive three miles to work, then it's off again till the same trip home after work).

Your winter mileage will be slightly worse because your A/C will be running when you use the defrost setting in most vehicles. Something to be aware of.

 

I didnt clean the maf. its a little hard to reach in the rx. but i bought a crc can lol.
how do i clean fuel injector ?
i didnt change any of the o2 sensor because i dont have any check engine light.

i know my winter mileage is a worse then summer but even my summer mps is bad
i use shell 89. i tried 91 and it didnt make any difference.

 

It's still worth the effort to pull the MAF and use a spray cleaner on it. As for the fuel injectors, unless you're a hard care mechanic I wouldn't recommend it and leave it to a mechanic, but the downside is it's an expensive job so you get diminishing returns on the gas saved. Still, fuel injected engines function better at freeway speeds, and city driving will tend to gum up the injectors. That's a tough call.

If you have an O2 sensor that is failing/degraded may not necessarily cause your engine to throw out a code. Again, you have to weigh the cost of a new O2 sensor/s and the labor versus the potential mileage improvement which, IMO, could be as high as 20%.

 

Yesterday i spoke with a guy from my area who also drive an rx350 and he said he is getting 13-15 l/100km. Same car same city same environment and im getting 23-24 l/100km.
After the holiday im taking the car to my mechanic.
I hope its gonna be easy to diagnose.

 

Odd you were living with that high consumption for so long. No details on mileage power train etc etc or any routine maintenance done over time.

It depends on a lot and I doubt any one thing is responsible for it. IMO

Everything from the Air filter, gas brand, driving habits and the vehicle itself.

To me I'd say take it to a reputable shop equivalent to a dealer with full diagnostic equipment or a Toyota dealer and spend the hours labour charge to have it checked out. Wheels can be done by them quite quickly and they can scan the computer for codes and see if its running rich for example amongst other things. There is far too many factors and take a good DIY a week to cover weather permitting.

 

My car is a 2010 with 120000 km (80K miled). The car is under warranty till april 2018 with lexus. The previous owner bought an 8 year extended warranty.

My mechanic is very competent and have all scanner and computer needed. I wiill give him the car to get a diagnostic and if its covered by warranty ill take it lexus to get it repaired. Almost everythung is still covered like sensor, caliper, bearing ...

 

Well if the filters and general maintenance items are as they should be and no wheel issues contributing to the high fuel consumption. It should then go to Toyota to test and inspect.

they won't do anything he might say without testing and confirming themselves. Dealer never do believe a fault is what the owner or other mechanic says. They have to determine it themselves especially for warranty repairs.

There for if you're using the correction oil filter and spec's 0W20 synthetic oil as well. The dealer will look for areas that are off spec including O2 sensors amongst other items. The L/100 is way above the norm and must be a lot of carbon somewhere after that time running.