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4RX Mileage Thread

 
Old 03-20-16, 08:30 PM
  #46  
SEW
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Hello. This is my first post. I've owned a 2006 RX400h 4WD for 5 years and have a 2016 RX350 on order.
Sorry for the following negativity, but I was disappointed in the 28+ minute CBC Marketplace film. Unfortunately, it didn't take a sicientific approach at all: especially the first Dino test. It'll take the same power to maintain a certain speed regardless of octane. What should have been measured was the fuel flow to maintain that speed. Of course, the power required would remain the same! Secondly, never discussed or explained , or understood??, the compression ratios of reg fuel requiring engines vs premium requiring engines with conventional fuel injection (nearly all cars) verses direct injection engines(2016 RX350, ? RX450h) which can handle various octane fuels more gracefully than more traditional fuel injected or carberatored engines .
Engines designed for higher octane fuels generally do better with the higher octane while lower compression engines actually do better, as they stated, with lower octane - that part is dead on in the film. Even my 2015 RAM 1500 (V-6) owner's manual specifically states to use 87 Octane and not higher. First time I've actually seen this in print.
My opinion and experience as an owner and mechanic is use what the manual recommends. Few gas station attendants are serious automotive authorities.

Last edited by SEW; 03-21-16 at 08:02 PM.
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Old 03-20-16, 09:48 PM
  #47  
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Why not just post average MPH with MPG?
For example with 20MPH one will get 15MPG,
with 25MPH it will increase to 16-17 and so on.
For one person 5 miles commute could be 5 min for another 10 min and for 3rd 15 min, even though it is same distance commute is totally different and so is the MPG.
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Old 04-06-16, 08:04 PM
  #48  
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Miles per gallon for a full tank on a 2016 Lexus RX 350 while city driving with lots of stops and 35-40 mph with 18" wheels and Bridgestone Ecopia tires filled to recommended pressure 33 psi. 4th full tank will be with 20" f sport graphite wheels with Michelin Premier LTX on 38 psi.


1st tank 15.6 Normal mode OEM gas
2nd tank 16.2 Eco mode 7-Eleven regular gas
3rd tank 15.5 Eco mode Racetrac regular gas
4th tank 16.5 Eco mode 7-Eleven Regular gas (switch to 20" and 38 psi from 18" and 33 psi)
5th tank 18.3 Normal mode 7-Eleven regular gas (75% tank=13 gallons and 245 miles = 18.8 mpg
6th tank "20.1" so far few miles driven Sport mode 7-Eleven regular gas

Is this due to the differences between winter gas and summer gas like someone mentioned??? How do you leave Sport mode permanently on? Do you have to manually set Sport mode every time you start the car? Hope not because Sport saves more gas than ECO and Normal mode in my type of driving granny style cruising slowly towards a red light while everybody around me races to see who stops first in the queue. Will try ECO with summer gas next.

My manual gas calculation provides better gas mileage than what the car computer says but not by much.

I have the 2016 Lexus RX 350 base with 20" F Sport wheels.
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Old 04-07-16, 06:43 AM
  #49  
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Originally Posted by LordBowral View Post
They recommend the lowest grade the car will run on to appeal to buyers so they can make it s eem cheaper to run ... It makes the engine internals dirty and sticky where's higher octane is much cleaner and most importantly creates better performance . If you appreciate engineering treat it to the best and get better performance and mileage
oh get over it. RX and Highlander have the same engine. Its not a magic engine.

If the manual says regular, it will run on regular.

16.2mpg in local town drive...eco mode. I've gotten 25mpg or so for highway driving
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Old 04-07-16, 12:54 PM
  #50  
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Originally Posted by LordBowral View Post
They recommend the lowest grade the car will run on to appeal to buyers so they can make it s eem cheaper to run ... It makes the engine internals dirty and sticky where's higher octane is much cleaner and most importantly creates better performance . If you appreciate engineering treat it to the best and get better performance and mileage

How would premium gas provide better performance if it is not necessary for this engine? The higher the octane, the less energy is stored in every gallon of gasoline.
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Old 04-07-16, 01:14 PM
  #51  
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Originally Posted by toyotaman7 View Post
How would premium gas provide better performance if it is not necessary for this engine? The higher the octane, the less energy is stored in every gallon of gasoline.
According to people in the bmw forums, drivers who put lower octane gas reported worse MPG and less power. The gas attendant one put regular gas once in my bmw and there was a more sluggish feel....not sure about worse mpg. With the RX, I doubt there is any better mpg....maybe slightly more pep
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Old 04-07-16, 01:18 PM
  #52  
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BMW's require premium grade and performance degrade with regular. The RX is design for regular so it performs as stated. It will not improve with premium. That's my belief and I'm sticking to it!
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Old 04-07-16, 01:45 PM
  #53  
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Originally Posted by sirtiger View Post
According to people in the bmw forums, drivers who put lower octane gas reported worse MPG and less power. The gas attendant one put regular gas once in my bmw and there was a more sluggish feel....not sure about worse mpg. With the RX, I doubt there is any better mpg....maybe slightly more pep
If the engine is designed for higher octane and received lower octane, the timing will be off. The computer will adjust the timing and by doing so performance will be sacrificed.

However, if the engine is designed for regular then it can handle regular gas without having to adjust the timing.
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Old 04-07-16, 02:10 PM
  #54  
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Originally Posted by dchar View Post
The RX350 only requires regular and the RX450h requires premium.
I haven't done the math on this one but wouldn't this negate buying the hybrid version for fuel savings?
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Old 04-07-16, 03:17 PM
  #55  
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Originally Posted by NRX View Post
I haven't done the math on this one but wouldn't this negate buying the hybrid version for fuel savings?
In Ontario we pay about 15% premium for premium gas. So the fuel economy improvement had to be more than that, assuming hybrid and gas would be the same price, which they are not.
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Old 04-07-16, 05:05 PM
  #56  
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Originally Posted by NRX View Post
I haven't done the math on this one but wouldn't this negate buying the hybrid version for fuel savings?
I thought the same thing....at that level, there isn't any savings
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Old 04-08-16, 06:06 PM
  #57  
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Originally Posted by NRX View Post
I haven't done the math on this one but wouldn't this negate buying the hybrid version for fuel savings?
There's no real amount of fuel savings that would cost justify the hybrid (I had the 400h)... It's more about environment than savings.
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Old 04-11-16, 11:57 AM
  #58  
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Disappointed in MPG!

Took my wife's car on a recent road drip, LA to Carlsbad (San Diego). Car has a little over 3K miles, filled up regular as we were heading out. 95% highway with 70-80MPH most of the time (little traffic). Trip miles driven: 290. MPG: 24.1 (per computer).

I really expected close to the 28 MPG. My other RX350 (2009 model) is rated 18/23 continuously gets 24 on my commute (mostly freeway).

We just moved and our daily work commutes have more than doubled. 2016 RX's MPG was one of the main reason why we choose the vehicle. I feel like false advertising...
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Old 04-11-16, 01:56 PM
  #59  
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Originally Posted by noeldavid View Post
310 miles divided by 19.2 gallon tank size = 16.2 mpg
Fill up your tank.
Re-set trip odometer
Fill up again and write down the exact amount of gallons shown on the pump.
Take the odometer reading and divide by the amount of gallons shown from the pump.
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Old 04-11-16, 02:12 PM
  #60  
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Originally Posted by rusn007 View Post
Disappointed in MPG!

Took my wife's car on a recent road drip, LA to Carlsbad (San Diego). Car has a little over 3K miles, filled up regular as we were heading out. 95% highway with 70-80MPH most of the time (little traffic). Trip miles driven: 290. MPG: 24.1 (per computer).

I really expected close to the 28 MPG. My other RX350 (2009 model) is rated 18/23 continuously gets 24 on my commute (mostly freeway).

We just moved and our daily work commutes have more than doubled. 2016 RX's MPG was one of the main reason why we choose the vehicle. I feel like false advertising...
It's not run in yet so it will improve but are you really worried about a few mpg ??? Slow down if you want better mpg ... 70-80 is a very uneconomical speed
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