Anyone over 200k?
12-19-19, 01:09 PM
#17
Lexus Test Driver
Yes I am. Octane is a measurement of a fuel's resistance to igniting when compressed in an engine's cylinder. Raising octane allows engineers to increase the engine's compression ratio, which is one of the higher ones out there in our GS at 11.8 : 1, which in turn enables an engine to run with greater thermal efficiency and produce more power from less fuel. We are not talking something major here but a difference nevertheless.
Oh I hear ya
Bclexus likes to be the smartest guy in the room
Oh I hear ya
Bclexus likes to be the smartest guy in the room What I question is how (as you suggest) the GS 350's onboard mpg and mileage range computer is able to immediately determine that 93 octane was just [literally] pumped into the fuel tank (when 91 octane gasoline had been used in the previous tank full) ...and recalculates an increased mileage range based on having just filling the tank. That does not make any sense to me. I think the mileage range computer determines the range based on usage history, not future estimates based on gasoline octane that has not even been used yet.
Let's say that I have been using 87 octane gasoline for months and running almost on empty I pull into a gas station and fill-up with 93 octane. I am used to seeing my mileage range (on the display) with a full tank of gas being around [say] 350 miles with mostly city driving. You are telling me that the GS 350's onboard mpg and mileage range computer is able to immediate detect that I have put 93 octane gasoline in the tank and the computer now calculates an [increased] mileage range of say 390 miles (25-40 increased miles in range) based on that? Would the onboard mpg and mileage range computer provide that recalculated information, as you understand it, if I only turned the ignition to On and checked the mileage range without ever even starting the engine which would prevent the engine's ECU to get a 'taste' of the gasoline octane? Again, that does not any sense to me.
PS - I'll refrain from commenting on the snarky remark!
Last edited by bclexus; 12-19-19 at 01:36 PM.
12-19-19, 01:27 PM
#18
Lexus Test Driver
Oh no. Another controversial subject to encounter. Time for the popcorn. In one corner, 93 is hardly any different than 91. In the other corner, 93 is even better than 91, so unlike aspirin, the more, the better. Ready, GO! (And I am only joking folks. I enjoy the discussions as usually both sides have good points, and there just may not be a definitive answer).
12-19-19, 01:46 PM
#19
Well the issue is that you're nitpicking at every possible detail and what is different to that of your experience and refuse to recognize that someone might have had a different experience. If you read carefully, bob256k never said the full tank reading was immediately as he pressed the start button. Could have been a mile down the road. ECU's in today's cars are fast and are able to adjust many parameters hundreds of times per second. For cryin' out loud let the guy be happy with his few extra miles of range and not try to prove him wrong!
12-19-19, 02:04 PM
#20
Lexus Test Driver
Well the issue is that you're nitpicking at every possible detail and what is different to that of your experience and refuse to recognize that someone might have had a different experience. If you read carefully, bob256k never said the full tank reading was immediately as he pressed the start button. Could have been a mile down the road. ECU's in today's cars are fast and are able to adjust many parameters hundreds of times per second. For cryin' out loud let the guy be happy with his few extra miles of range and not try to prove him wrong!
12-19-19, 02:11 PM
#21
Instructor
I never knew i would learn so much (patience) from this forum lol. If i can get 93 ill take 93. if i cant' get 93, ill take 91. Y'all have a good thrusday!
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JDR76 (12-19-19)
12-19-19, 03:36 PM
#22
Lexus Test Driver
Completely agree regarding the LACK of 93. I drove to Oregon and filled up with 93, same brand of gas I use here, Costco. The different was amazing, and my mpg when calculated was about 33 mpg on the freeway @ 80 mph! The car said i had a 350 mile range, about 25-40 miles more than typical.
Last edited by bclexus; 12-19-19 at 05:54 PM.
12-19-19, 03:45 PM
#23
Lexus Champion
I have a thought about that...
In my GS, after fill-up, it usually says about 295 miles of range. A little higher if I drove a lot of highway miles on the last tank. I believe it sets the range based off of the average mileage on your previous tank.
When I take a road trip to Oregon, I always fill up before leaving Seattle. I usually get about 18 mpg around town, but I easily get 28 mpg on that drive.
Then I fill up in Portland before heading home, but because my previous tank average was high (28 ish), the range will now show something around 340 miles.
Seems like this may have been the same situation as Bob. Thoughts?
In my GS, after fill-up, it usually says about 295 miles of range. A little higher if I drove a lot of highway miles on the last tank. I believe it sets the range based off of the average mileage on your previous tank.
When I take a road trip to Oregon, I always fill up before leaving Seattle. I usually get about 18 mpg around town, but I easily get 28 mpg on that drive.
Then I fill up in Portland before heading home, but because my previous tank average was high (28 ish), the range will now show something around 340 miles.
Seems like this may have been the same situation as Bob. Thoughts?
12-19-19, 03:46 PM
#24
Instructor
OK , so drove from NorCal to Oregon , I filled up in Redding before getting to Oregeon, same mpg per tank as usual, i think it was after the second fill-up in Oregon I got 350 mile range. I usually only let it get to half a tank, so the first fill was 50% 91 50% 93, and the second fill-up of Costco gas was all 93 Oregon gas. By that second fill-up it was a honest mix of both highway and city driving , probably 35/65, as I was in ashland medford area, which is a halfway point to Seattle. On the second fill-up immediately after start the car showed the increased range.
I came to my 32 mpg calc by using the miles traveled divided by how many gallons it took to fill the tank, given i left my starting point with a full tank. I used google maps to get the distance traveled, the same GPS i use when driving , and i stopped when i was @ half a tank at a gas station about 45 minutes outside of Eugene When I say full, I mean FULL. I fill until the tank cant take anymore at least 5 clicks of the pump, and the gas gauge is always pinned to F.
I came to my 32 mpg calc by using the miles traveled divided by how many gallons it took to fill the tank, given i left my starting point with a full tank. I used google maps to get the distance traveled, the same GPS i use when driving , and i stopped when i was @ half a tank at a gas station about 45 minutes outside of Eugene When I say full, I mean FULL. I fill until the tank cant take anymore at least 5 clicks of the pump, and the gas gauge is always pinned to F.
Last edited by bob256k; 12-19-19 at 03:49 PM. Reason: Edited to add more detail and spelling ( cant type on this new keyboard)
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JDR76 (12-19-19)
12-19-19, 03:55 PM
#25
Lexus Test Driver
I have a thought about that...
In my GS, after fill-up, it usually says about 295 miles of range. A little higher if I drove a lot of highway miles on the last tank. I believe it sets the range based off of the average mileage on your previous tank.
When I take a road trip to Oregon, I always fill up before leaving Seattle. I usually get about 18 mpg around town, but I easily get 28 mpg on that drive.
Then I fill up in Portland before heading home, but because my previous tank average was high (28 ish), the range will now show something around 340 miles.
Seems like this may have been the same situation as Bob. Thoughts?
In my GS, after fill-up, it usually says about 295 miles of range. A little higher if I drove a lot of highway miles on the last tank. I believe it sets the range based off of the average mileage on your previous tank.
When I take a road trip to Oregon, I always fill up before leaving Seattle. I usually get about 18 mpg around town, but I easily get 28 mpg on that drive.
Then I fill up in Portland before heading home, but because my previous tank average was high (28 ish), the range will now show something around 340 miles.
Seems like this may have been the same situation as Bob. Thoughts?
What you describe is the way I think the Cruising Range mileage is calculated, which has nothing to do with octane of the gasoline - octane of the gasoline either previously used, or octane of the gasoline that the car was just filled-up with.
12-19-19, 08:41 PM
#26
Lexus Test Driver
I was getting 26-27 MPG on my Thanksgiving holiday trip until some fool in a BMW tried to race me then it all dropped to 16 MPG. 
12-20-19, 03:04 AM
#27
I personally don't think 2 octane points makes any difference with the ECU, the horsepower curve or the MPG achieved unless the engine is operated at or near WOT or under a heavy load.
I always use 93 octane as well. If I have recently been on a highway trip that provides increased fuel mileage when I fill-up I often notice that my mileage range has increased. I have no other explanation for the increased mileage range other than [that] the most recent trip had provided better fuel mileage, so when I filled-up the onboard computer calculated that I would achieve greater mileage range due to having had better mpg on the most recent trip.
Are you suggesting that as soon as you fill-up with 93 octane (when you had been using say 91 octane) that the car's computer is somehow able to immediately detect it has 93 octane in the tank - and that (increased octane) is why the mileage range increases?
I always use 93 octane as well. If I have recently been on a highway trip that provides increased fuel mileage when I fill-up I often notice that my mileage range has increased. I have no other explanation for the increased mileage range other than [that] the most recent trip had provided better fuel mileage, so when I filled-up the onboard computer calculated that I would achieve greater mileage range due to having had better mpg on the most recent trip.
Are you suggesting that as soon as you fill-up with 93 octane (when you had been using say 91 octane) that the car's computer is somehow able to immediately detect it has 93 octane in the tank - and that (increased octane) is why the mileage range increases?
I drive to from Palm Beach to Orlando every couple of months and average about 24-25 mpg, a 375 mile round trip. After filling up, the range goes to the 370s. Local driving nets me 21-22 and the range is usually in the 330-340s. So to me, the last tank's mpg is the factor that influences the range estimator.
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jonathancl (12-20-19)
12-20-19, 08:42 AM
#29
12-20-19, 10:57 AM
#30
Lexus Test Driver
Originally Posted by bclexus View Post
I personally don't think 2 octane points makes any difference with the ECU, the horsepower curve or the MPG achieved unless the engine is operated at or near WOT or under a heavy load.
I always use 93 octane as well. If I have recently been on a highway trip that provides increased fuel mileage when I fill-up I often notice that my mileage range has increased. I have no other explanation for the increased mileage range other than [that] the most recent trip had provided better fuel mileage, so when I filled-up the onboard computer calculated that I would achieve greater mileage range due to having had better mpg on the most recent trip.
Are you suggesting that as soon as you fill-up with 93 octane (when you had been using say 91 octane) that the car's computer is somehow able to immediately detect it has 93 octane in the tank - and that (increased octane) is why the mileage range increases?
I personally don't think 2 octane points makes any difference with the ECU, the horsepower curve or the MPG achieved unless the engine is operated at or near WOT or under a heavy load.
I always use 93 octane as well. If I have recently been on a highway trip that provides increased fuel mileage when I fill-up I often notice that my mileage range has increased. I have no other explanation for the increased mileage range other than [that] the most recent trip had provided better fuel mileage, so when I filled-up the onboard computer calculated that I would achieve greater mileage range due to having had better mpg on the most recent trip.
Are you suggesting that as soon as you fill-up with 93 octane (when you had been using say 91 octane) that the car's computer is somehow able to immediately detect it has 93 octane in the tank - and that (increased octane) is why the mileage range increases?
I agree with the former statement and strongly doubt the latter.
I drive to from Palm Beach to Orlando every couple of months and average about 24-25 mpg, a 375 mile round trip. After filling up, the range goes to the 370s. Local driving nets me 21-22 and the range is usually in the 330-340s. So to me, the last tank's mpg is the factor that influences the range estimator.
I drive to from Palm Beach to Orlando every couple of months and average about 24-25 mpg, a 375 mile round trip. After filling up, the range goes to the 370s. Local driving nets me 21-22 and the range is usually in the 330-340s. So to me, the last tank's mpg is the factor that influences the range estimator.
