rohanp

No error codes. I did an emission test and its fine low Carbon Monoxide levels. It means combustion is complete. Could the high fuel consumption be attributed to a clogged or dysfunctional catalytic converter?

geometrix

Dear Forum,

I have read multiple posts on this forum about gas mileage on a 2000 Lexus RX300 AWD, and I do not see any clear cut culprits (oxygen sensors, A/F sensors, tires are properly inflated, etc???). I think that my gas mileage is worse than anybody else describes.

I recently purchased my 2000 Lexus RX300 AWD with ONLY 36,000 miles. It had an excellent CarFax with all service records. The only major item that had not been addressed was the timing belt. So I had JM Lexus in Margate, FL change the timing belt, water pump, camshaft seals, crankshaft seal, and both drive belts.

The car runs great, but I am only getting 14.8 mpg at best. The documented gas mileage for this vehicle is 16mpg City / 21mpg Highway with 18mpg combined City/Highway. I am driving the vehicle in combined City/Highway driving. I have no CEL's.

I was thinking about pouring a bottle of STP fuel injector cleaner in the gas tank. Will this do anything? Will this harm the engine and/or seals and gaskets?

Any advice is greatly appreciated.

--Neal

sktn77a

iTrader: (2)

I'd go Techron over STP. Won't do any harm but I doubt it will have any positive effect. Have you changed the engine air filter? Cleaned the AIC? I got 22 MPG when ours was new but get 18 at best now. In the city, its more like 16 (at 220,000 miles). With a lead foot I'm sure I could get that down below 14.8!

geometrix

Dear sktn77a,

I may still try the Techron just for the hell of it.

I checked the engine air filter when I purchased the car about 5 weeks ago and it is brand new.

AIC? I looked on this forum for this acronym. Do you mean IAC - Idle Air Control Valve? I am asking this just to be sure that we are talking about the same thing.

I just watched a great video on YouTube cleaning the IAC valve on a 2002 RX300:
I can do this.

Thank You,
--Neal

bigjon42

I have a 1999 RX300 fwd 204,000 miles and get 21+ mpg. 10% city, 90% hiway or rural roads. Not a lead foot. 70+ mph on hwy.

geometrix

Hey Bigjon42,

How are you getting such good mileage? Any special motor oil? Gas octane rating? etc.?

--Neal

slothman

I get 21 to 22 mpg. 15 is pretty low.

Have you measured the mileage manually? IE fill tank to the top, drive it to quarter tank, full up again, and calculate ?

geometrix

Dear Slothman,

YES. This is the only way I have calculated mileage. I fill the tank, reset the trip odometer, run the tank to about empty, fill the tank back up, and then divide the miles traveled (trip odometer) divided by the number of gallons that I used to fill the tank back up.

--Neal

maxSteel

One contributor is the change in gas formulation since then. Current blended regular gas produces less MPG.

bigjon42

Bigjon here again. I get 21-22+ by driving style, (conservative), premium fuel, and NO lead foot. No addatives, I do dive 70+ on the freeway.

CharBaby

I am surprised to see this thread was reserected when it arrived in my email.
We bought a new RX300 in 2001 and the fuel economy was never anywhere near the EPA figures. Ohh, maybe a couple of times ever in 14 yrs of ownership did we get some fliers. I think ONLY ONCE did we get 23-24 on the hiwy and maybe 18-19 city. And my wife & I typically meet or excede(and sometime even trounce) the EPA rating for our other vehicles. So, ya can't blame the driving style or climate.

However I have heard of others getting their EPA rating or even above. Ours was more along the lines of 16 city/19 hiwy, not the 18/22 that it was rated for. And the dismal fuel economy we achieved was with a light foot... Even since new. So no need for fuel system cleaners, TB cleaning, IAC cleaning. The economy just wasn't very good in this SUV.

ATMOF(and I've voiced my opinion to another member/friend at CL) I never thought that the 1st gen RX was anything to write home about...at least with our 2001. We had issues from year 2 and they never stopped until I sold it in 2015. Also, I didn't find that the RX(my wife's car) rode, handled nor was a quiet vehicle for the $40,000 we paid 20 years ago. My wife's sister had the same year RX(also a 2001) and she was almost as disappointed with this RX's reliability as any of her BMWs as well as her complaints for not feeling like a LEXUS should; smooth/quiet/good riding.

I just never got that LEXUS experience with this RX, which should have sealed my love for LEXUS. Lots of problems, poor fuel economy, poor ride, sloppy cornering even in mild turn-in, numb/sloppy steering feel, mushy brakes, loud on the hiwy, crashy over bumps(poor bump absorption). And I kept some seriously good riding tires on this SUV. It just didn't help.

And I was so HIGH when we first bought it and I can't believe...what a let down it was. And every one of my LEXUS forum friends made excuse after excuse for my problems. Yeah OK!

geometrix

Dear sktn77a,

I stopped by O'Reilly Auto Parts yesterday. They did not have Techron Fuel Injector Cleaner, but they did have STP Fuel Injector Cleaner. So I purchased the STP.

As I was getting into my car, a man who just parked his car said, "Don't put this s#@t in your car. Use Lucas Fuel Injector Cleaner."

I asked why, and he stated that he used STP and it gummed up his injectors. He said that because of this, he had to replace all of his injectors. He also said that these companies (e.g. STP) will sell anything just to make a "buck" and that I should return the STP Fuel Injector Cleaner and buy the Lucas Fuel Injector Cleaner.

Any opinions?

TIA,
--Neal

CharBaby

If the STP has PEA in it, you'll be fine. I've used it in the past without a single issue.

PSURobert

Totally agree with CharBaby that the RX was overrated, but it was the template for the crossover suv mass market movement. Our '01 was a pleasant, roomy car that was great as an interstate hauler, but it never got over 22 mpg, and usually closer to 20 mpg. As others said, exceeding 70 mph sacrificed fuel economy. My wife loved the looks of "her car" but neither of us enjoyed the large turning circle radius of such a short car. Although I changed the oil religiously using high-quality detergent grade (non-synthetic) the car suddenly succumbed to the dreaded oil sludge problem at 150K, but too late in time to qualify for the settlement. We're still a little nostalgic when we see a pearly white one on the road, but our '15 Toyota Highlander is more satisfying overall.

CharBaby

Ours too was pearl white metallic with tan/cocoa interior & gold emblem pkg including the grill. She was pretty but what a “B”itch