The 3RX Gas Mileage Thread
Lexus Champion
Joined: Aug 2007
Posts: 4,507
Likes: 38
From: Bethlehem Twsp. Pennsylvania
I have posted this before in this thread but it has been awhile so I will repeat.
I have tried numerous experiments with regular vs. premium gas and have never seen any
noticeable difference. Doing the math, premium is usually .30-.40 cents more per gallon and the mpg increase would need to be significant to just break even. But it never helps. I think your dealer is making up an answer about breaking in the engine. That was in the old day, not before synthetic oil.
My service advisor used to work for Mobil. He told me that mpg would depend more on the cleanliness of the fuel and if the gas stations are changing their filters. He recommends staying with a major oil company and using a busy station that gets a lot of attention from the distributors.
Also, all us in the winter climates have to deal with Winter Mix gas. That will effect your MPG more than anything else. I will see a 3-4 mpg increase once the fuel mix is changed to a summer mix.
Overall, many, including me, have been disappointed in the mpg on the RX 350. A few tricks I have used to help.
Overinflated the tires - SLIGHTY - by about 2-3 lbs. This made a difference.
Use cruise control whenever possible.
Careful on acceraltions from a dead stop as this is a fuel burner.
Keep weight in car at a minimum. Remove anything heavy from trunk
Driving with windows and sunroof closed actually helps by a 1mpg.
Have the "dealer" explain to you specifically why he thinks it will improve with "break in". Ask
where he gets his info? This is old school thinking, like wearing clean underwear in case you
need an ambulance
Save your money on premium fuel. Trust me, it doesn't help.
I have tried numerous experiments with regular vs. premium gas and have never seen any
noticeable difference. Doing the math, premium is usually .30-.40 cents more per gallon and the mpg increase would need to be significant to just break even. But it never helps. I think your dealer is making up an answer about breaking in the engine. That was in the old day, not before synthetic oil.
My service advisor used to work for Mobil. He told me that mpg would depend more on the cleanliness of the fuel and if the gas stations are changing their filters. He recommends staying with a major oil company and using a busy station that gets a lot of attention from the distributors.
Also, all us in the winter climates have to deal with Winter Mix gas. That will effect your MPG more than anything else. I will see a 3-4 mpg increase once the fuel mix is changed to a summer mix.
Overall, many, including me, have been disappointed in the mpg on the RX 350. A few tricks I have used to help.
Overinflated the tires - SLIGHTY - by about 2-3 lbs. This made a difference.
Use cruise control whenever possible.
Careful on acceraltions from a dead stop as this is a fuel burner.
Keep weight in car at a minimum. Remove anything heavy from trunk
Driving with windows and sunroof closed actually helps by a 1mpg.
Have the "dealer" explain to you specifically why he thinks it will improve with "break in". Ask
where he gets his info? This is old school thinking, like wearing clean underwear in case you
need an ambulance
Save your money on premium fuel. Trust me, it doesn't help.
Sorry, but i respectfully disagree ^^^ when i use the 89 octane, i can feel a big difference in the engines performance. the millage is maybe .5-1.0 mpg more as well.
Rookie
Joined: Aug 2013
Posts: 92
Likes: 1
From: Ny
Picked up my 2015 RX450 last March. Drove the first 2000 miles on regular gasoline-Sunoco--my mpg was excellent at about what it is now. That being around 26-27 non highway. TheN I read these blogs and people were saying better mpg with higher grade fuel. Ok-- so the next fill up I moved up two grades with the Sunoco gasoline. I don't recall the difference in octane,but it was much higher. So-- off I go figuring my mpg is going to be better than what it already was. Well--- I could not have been more wrong. Remember-- this is now getting into warmer weather and the summer blend gasoline compared to the weather and winter grade I was achieving the 26-27 mpg with. My mpg dropped down to the 19-21 range-- consistently. What the heck!!! The mpg stayed like that no matter what I did. I went back to regular grade and the mpg still stayed in that lower range. Did not tick up at all. Went through summer into winter and now spring. Walla--- just two weeks ago my mpg went back up to 26-27 and a bit better. Still all non highway. It is now consistently in that range. I have no idea why that happened but this really what happened. For some reason that higher octane gas screwed up,the computer-- I think. Any ideas out there. I can't come up with any other ideas except for the computer. I guess my last thought would be---- stick with the regular---'don't mess with success. I will never put higher grade in the tank again. I learned my lesson.
Lexus Champion
Joined: Aug 2007
Posts: 4,507
Likes: 38
From: Bethlehem Twsp. Pennsylvania
From my own experience,this is what took place.
Picked up my 2015 RX450 last March. Drove the first 2000 miles on regular gasoline-Sunoco--my mpg was excellent at about what it is now. That being around 26-27 non highway. TheN I read these blogs and people were saying better mpg with higher grade fuel. Ok-- so the next fill up I moved up two grades with the Sunoco gasoline. I don't recall the difference in octane,but it was much higher. So-- off I go figuring my mpg is going to be better than what it already was. Well--- I could not have been more wrong. Remember-- this is now getting into warmer weather and the summer blend gasoline compared to the weather and winter grade I was achieving the 26-27 mpg with. My mpg dropped down to the 19-21 range-- consistently. What the heck!!! The mpg stayed like that no matter what I did. I went back to regular grade and the mpg still stayed in that lower range. Did not tick up at all. Went through summer into winter and now spring. Walla--- just two weeks ago my mpg went back up to 26-27 and a bit better. Still all non highway. It is now consistently in that range. I have no idea why that happened but this really what happened. For some reason that higher octane gas screwed up,the computer-- I think. Any ideas out there. I can't come up with any other ideas except for the computer. I guess my last thought would be---- stick with the regular---'don't mess with success. I will never put higher grade in the tank again. I learned my lesson.
Picked up my 2015 RX450 last March. Drove the first 2000 miles on regular gasoline-Sunoco--my mpg was excellent at about what it is now. That being around 26-27 non highway. TheN I read these blogs and people were saying better mpg with higher grade fuel. Ok-- so the next fill up I moved up two grades with the Sunoco gasoline. I don't recall the difference in octane,but it was much higher. So-- off I go figuring my mpg is going to be better than what it already was. Well--- I could not have been more wrong. Remember-- this is now getting into warmer weather and the summer blend gasoline compared to the weather and winter grade I was achieving the 26-27 mpg with. My mpg dropped down to the 19-21 range-- consistently. What the heck!!! The mpg stayed like that no matter what I did. I went back to regular grade and the mpg still stayed in that lower range. Did not tick up at all. Went through summer into winter and now spring. Walla--- just two weeks ago my mpg went back up to 26-27 and a bit better. Still all non highway. It is now consistently in that range. I have no idea why that happened but this really what happened. For some reason that higher octane gas screwed up,the computer-- I think. Any ideas out there. I can't come up with any other ideas except for the computer. I guess my last thought would be---- stick with the regular---'don't mess with success. I will never put higher grade in the tank again. I learned my lesson.
hate to break this to you. but the 450 requires premium fuel....
Rookie
Joined: Aug 2013
Posts: 92
Likes: 1
From: Ny
Agrees
Per my 2015 RX450 hybrid owners manual----
Unleaded gasoline of 87 octane may be used. This is the Sunoco grade I use. Just checked at the gas station. When I picked up,the car I remember the service people telling me that regular was fine. In fact thats what the dealer filled it up with. I'm not going to argue the point. I'm just telling you what took place with my hybrid. Mine runs fine on regular just like they told me. When I went to higher octane the mpg dropped considerably for a long period even though after that first tank results,I returned to regular gasoline. It then took six months to return to the excellent mpg I was achieving
before the switch to that one tank of higer octane. For me----- it is what it is--- I'll stick to what works. The dealer fully agrees. Remember this is Sunoco grade. Many brands are at 86. That would not be recommended.
Per my 2015 RX450 hybrid owners manual----
Unleaded gasoline of 87 octane may be used. This is the Sunoco grade I use. Just checked at the gas station. When I picked up,the car I remember the service people telling me that regular was fine. In fact thats what the dealer filled it up with. I'm not going to argue the point. I'm just telling you what took place with my hybrid. Mine runs fine on regular just like they told me. When I went to higher octane the mpg dropped considerably for a long period even though after that first tank results,I returned to regular gasoline. It then took six months to return to the excellent mpg I was achieving
before the switch to that one tank of higer octane. For me----- it is what it is--- I'll stick to what works. The dealer fully agrees. Remember this is Sunoco grade. Many brands are at 86. That would not be recommended.
Driver School Candidate
Joined: Dec 2013
Posts: 21
Likes: 0
From: NH
RX 350 premium vs regular
I have, on numerous occasions, run the tank to nearly empty and filedl up with premium vs, regular fuel and maybe found 1 mpg improvement. Here is some simple math for an example:
14 gallons
x .30¢ (more per gallon)
______________
$4.20 more per fill up
14 gallons x 16 mpg = 224 miles per tank
14 galland x 17 mpg = 238 miles per tank
6 miles more per tank refill
17mpg/6 more miles = .35 gallons less gas
.35 gallons x $1.95 per gallon = $.68 savings
$4.20 more per fill up
- .$68 savings
_______
$3.52 more per tank fill
And in my 2010 (that recommends premium fuel) no noticeable difference. In addition no one at the dealer from the service advisor to a certified mechanic could explain why premium was recommend other than perhaps Lexus owners want to feel good about buying only premium products. That came right from the mechanic. I have been using regular gas for 6 years now and figured I have saved over $1,000. Just sayin.
14 gallons
x .30¢ (more per gallon)
______________
$4.20 more per fill up
14 gallons x 16 mpg = 224 miles per tank
14 galland x 17 mpg = 238 miles per tank
6 miles more per tank refill
17mpg/6 more miles = .35 gallons less gas
.35 gallons x $1.95 per gallon = $.68 savings
$4.20 more per fill up
- .$68 savings
_______
$3.52 more per tank fill
And in my 2010 (that recommends premium fuel) no noticeable difference. In addition no one at the dealer from the service advisor to a certified mechanic could explain why premium was recommend other than perhaps Lexus owners want to feel good about buying only premium products. That came right from the mechanic. I have been using regular gas for 6 years now and figured I have saved over $1,000. Just sayin.
Moderator
Joined: Dec 2003
Posts: 3,283
Likes: 63
From: FL
FWIW, I've found that when you change from regular to premium you need to run 2-3 tanks to see any real improvement as it takes the computer time to readjust to the higher octane. Going in the other direction is quicker as it detects pre-detonation and quickly readjusts to stop it.
Rookie
Joined: Aug 2013
Posts: 92
Likes: 1
From: Ny
I have, on numerous occasions, run the tank to nearly empty and filedl up with premium vs, regular fuel and maybe found 1 mpg improvement. Here is some simple math for an example:
14 gallons
x .30¢ (more per gallon)
______________
$4.20 more per fill up
14 gallons x 16 mpg = 224 miles per tank
14 galland x 17 mpg = 238 miles per tank
6 miles more per tank refill
17mpg/6 more miles = .35 gallons less gas
.35 gallons x $1.95 per gallon = $.68 savings
$4.20 more per fill up
- .$68 savings
_______
$3.52 more per tank fill
And in my 2010 (that recommends premium fuel) no noticeable difference. In addition no one at the dealer from the service advisor to a certified mechanic could explain why premium was recommend other than perhaps Lexus owners want to feel good about buying only premium products. That came right from the mechanic. I have been using regular gas for 6 years now and figured I have saved over $1,000. Just sayin.
14 gallons
x .30¢ (more per gallon)
______________
$4.20 more per fill up
14 gallons x 16 mpg = 224 miles per tank
14 galland x 17 mpg = 238 miles per tank
6 miles more per tank refill
17mpg/6 more miles = .35 gallons less gas
.35 gallons x $1.95 per gallon = $.68 savings
$4.20 more per fill up
- .$68 savings
_______
$3.52 more per tank fill
And in my 2010 (that recommends premium fuel) no noticeable difference. In addition no one at the dealer from the service advisor to a certified mechanic could explain why premium was recommend other than perhaps Lexus owners want to feel good about buying only premium products. That came right from the mechanic. I have been using regular gas for 6 years now and figured I have saved over $1,000. Just sayin.
What octane regular gasoline are you using.
My hybrid runs great "now" on the 87 grade Sunoco regular.
Intermediate
Joined: Sep 2014
Posts: 349
Likes: 40
From: Alberta
My findings from a 2011 RX350 with all-wheel-drive:
Idling these vehicles DECIMATES fuel economy. Mine is taken a short drive to work and it's not the stop & go that's killing it, it is the sitting through multiple light cycles at idle.
I have also repeatedly tested the 91 vs 87 octane mileage and I find that there is statistically zero difference.
The worst I can consistently get is 21L/100km = 11.2mpg... This is in winter with winterized gasoline with tons of idling. It's closer to 20L/100km in summer.
The best I can consistently get is 9.9L/100km = 23.8mpg... This is from 100% highway at about 120km/h = 75mph. I bet it would do better on the highway at lower speeds, maybe 80km/h.
Idling these vehicles DECIMATES fuel economy. Mine is taken a short drive to work and it's not the stop & go that's killing it, it is the sitting through multiple light cycles at idle.
I have also repeatedly tested the 91 vs 87 octane mileage and I find that there is statistically zero difference.
The worst I can consistently get is 21L/100km = 11.2mpg... This is in winter with winterized gasoline with tons of idling. It's closer to 20L/100km in summer.
The best I can consistently get is 9.9L/100km = 23.8mpg... This is from 100% highway at about 120km/h = 75mph. I bet it would do better on the highway at lower speeds, maybe 80km/h.
Last edited by ColAngus; Apr 17, 2016 at 08:58 PM.
Driver School Candidate
Joined: Dec 2015
Posts: 46
Likes: 1
From: CA
I just drove from San Francisco Bay Area to Los Angeles (I-5) and then to Scottsdale, AZ (I-10) - about 750 miles. I got an average of about 24 mpg overall, cruising at around 80 mph most of the time (virtually no heavy traffic to deal with). Temperature was is the 90s most of the way, but I'm not a heavy A/C user - always have the fan on lowest setting. Tires are at (cold) 32 psi. I was reasonably pleased with this. Used lowest octane gas.
PS this is a 2013 RX 350 with about 12k miles. I need to figure out how to add a signature
PS this is a 2013 RX 350 with about 12k miles. I need to figure out how to add a signature
Driver
Joined: Mar 2011
Posts: 55
Likes: 1
From: nY
My 2011 is till getting what I consider lousy milage out here on eastern LI . When its colder out in winter I get 16 mpg and when its warmer as in last month I get around 17-17.5. It is AWD but I am by no means in any kind of heavy stop and go city traffic. The Manager of the Lexus dealer had a 2011 and he was getting 18.5-19 in the same neighborhood. On the highway Ill get 26-28 if its really flat no traffic at 60 mph But 95 % of my driveing is local here not highway. Car is 5 years 3 months old with 52k on it . Aside from the lousy local milage and again its pretty sparse here , farms still exist here I am very happy with the car . Except for the fuel injector ticking. Thats another story lol.
Driver
Joined: Jun 2012
Posts: 85
Likes: 7
From: ga
I just bought a 2014 RX 350 with only 8800 miles on it. This first tank of gas delivered 19.5 in town. I added Tecron fuel system cleaner to the second tank and the mileage went up to almost 21 under the same conditions. This is on regular. We took it on the road this weekend and saw an average of 25. If you run over 75 mph it will drop to 23 on the computer. Remember you are in a very nice box! The next step will be a less restrictive air cleaner element. My experience with other cars including my wife's RX 450H has been a 1 mpg improvement. Better breathing reduces load and the engine is smoother. Not sure whether to use KN or dry APE.
Rookie
Joined: May 2013
Posts: 70
Likes: 3
From: FL
Gas source is very important
I'm just finding out how important the gas in your tank is, when related to gas mileage. My wife recently filled up at a brand new Costco in our area. Didn't know this until later. Instead of normal 18 mpg around town, we were barely getting 16 mpg. Instead of normal 23+ on highway, we were only getting around 20.5. As soon as we refueled, however, we were getting normal mileage again. Guessing new Costco tanks has some contamination issues.
Also, after another routine fueling from an out of state station, mileage jumped to 26 mpg highway. My supposition is that the amount of water (contaminates)....or ethanol....in your gas tank.....can drastically effect your mileage. Too easy to pick up a bad batch once and awhile.
Also, after another routine fueling from an out of state station, mileage jumped to 26 mpg highway. My supposition is that the amount of water (contaminates)....or ethanol....in your gas tank.....can drastically effect your mileage. Too easy to pick up a bad batch once and awhile.
Rookie
Joined: Aug 2013
Posts: 92
Likes: 1
From: Ny
I just bought a 2014 RX 350 with only 8800 miles on it. This first tank of gas delivered 19.5 in town. I added Tecron fuel system cleaner to the second tank and the mileage went up to almost 21 under the same conditions. This is on regular. We took it on the road this weekend and saw an average of 25. If you run over 75 mph it will drop to 23 on the computer. Remember you are in a very nice box! The next step will be a less restrictive air cleaner element. My experience with other cars including my wife's RX 450H has been a 1 mpg improvement. Better breathing reduces load and the engine is smoother. Not sure whether to use KN or dry APE.
Rookie
Joined: Aug 2010
Posts: 71
Likes: 0
From: Washington State
I'm averaging around 20-22 mpg with my RX for mixed city driving and highway. 25% of my daily commute is stop & go traffic in back roads and the rest is highway driving 65 - 70 mph. I use regular gas from Fred Meyer (subsidiaries of Kroger).
I would say my RX mpg is decent enough, compared to my previous CX-9 (17-18 mpg) and IS 350 (22-23 mpg).
I would say my RX mpg is decent enough, compared to my previous CX-9 (17-18 mpg) and IS 350 (22-23 mpg).
Rookie
Joined: Aug 2013
Posts: 92
Likes: 1
From: Ny
I'm averaging around 20-22 mpg with my RX for mixed city driving and highway. 25% of my daily commute is stop & go traffic in back roads and the rest is highway driving 65 - 70 mph. I use regular gas from Fred Meyer (subsidiaries of Kroger).
I would say my RX mpg is decent enough, compared to my previous CX-9 (17-18 mpg) and IS 350 (22-23 mpg).
I would say my RX mpg is decent enough, compared to my previous CX-9 (17-18 mpg) and IS 350 (22-23 mpg).