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"I had 2 regular fill ups and hand calculated 19.4mpg. [Tank was run down to 15 mile range before filling with premium.] I did 2 premium fill ups and hand calculated 22.1mpg. "... Very similar observation regarding mpg on my 1 month old 4RX... Non-Premium (87) was giving around 19.5 mpg and Premium (93) around 22.3 mpg (65% City + 35% Highway).
I wondered about the line in the owner's manual that said 87 octane or higher was required. So over the last month or so I did 3 weeks of regular fill ups and 3 weeks of premium fill ups. I had 2 regular fill ups and hand calculated 19.4mpg. [Tank was run down to 15 mile range before filling with premium.] I did 2 premium fill ups and hand calculated 22.1mpg. City to highway ratio was hand calculated based on average speed between fill ups to be between 55-60% city.
I also have a wireless OBD II reader that calculates HP and torque. Max HP on regular was 297hp at 6147rpm and 279ft/lb at 4208 rpm. Max HP on premium was 307 at 5742rpm and 297ft/lb at 3630 rpm. Numbers were generated in sport mode by flooring the car while merging onto the highway. Acceleration from roughly from 30mph to 80mph. The car determined the shifts but it appeared to be near redline (~6450rpm).
This wasn't a well controlled experiment but interesting none the less.
Wow, I was not expecting to see HP/Torque increases and especially not that much, that is amazing if that is the case! I could see the MPG improved but didn't think output would be.
Did you notice smoother shifting, etc. using premium? I am going to try premium and see if I notice anything based on your results from the OBD II reader, I have been using 91 and the car is about a month old. Thanks for this info.
Wow, I was not expecting to see HP/Torque increases and especially not that much, that is amazing if that is the case! I could see the MPG improved but didn't think output would be.
Did you notice smoother shifting, etc. using premium? I am going to try premium and see if I notice anything based on your results from the OBD II reader, I have been using 91 and the car is about a month old. Thanks for this info.
I wasn't expecting it either. The car feels more responsive with premium and that may be attributable to the increase in torque at lower RPM. If I have time I'll graph the HP/torque with regular and premium together. I'd like to see if there is increased power everywhere or just at the peaks.
Done many mileage tests using both fuels, no difference. Car runs the same with reg as it does with premium. I do run a tank of premium for the cleaning properties every 4-5 tanks and to help with the potential for freezing in the winter.
I have never noticed any appreciable difference in performance, other than my 600hp truck that dynos a few HP more with race gas.
Done many mileage tests using both fuels, no difference. Car runs the same with reg as it does with premium. I do run a tank of premium for the cleaning properties every 4-5 tanks and to help with the potential for freezing in the winter.
I have never noticed any appreciable difference in performance, other than my 600hp truck that dynos a few HP more with race gas.
For a more authoritative result you can look at the lexus press release spec sheet comparing 2011 vs 2012-2015 models. Before and after the fuel recommendation switch but with same engine. I think that is as definitive as you're going to get in terms of how much improvement you should expect. You then extrapolate the same gains for 4th gen (1.9% and 3.6% increase)
Even if you got slightly more power and a little more gas mileage, Premium now cost way too much compared to regular.
Your new Lexus is delivered with regular gas and it will run just fine on it. At todays cost for Premium, I bet it sits in the station's underground tanks so long that you are not getting what you paid for.
This whole subject is like a religious thing and each must believe in what they want.
Higher octane fuel is just its resistance to knock or pinging. You can get slighty better performance but it will have nothing
to do with transmission shifting.
The GS 350 uses the SAME engine as the RX 350. GS 350 uses 91 Octane Premium and gets more HP and Torque. I think your will get the same performance if you put 91 octane in the RX 350.
I find that rolling in the city with regular, it's hard to accelerate at stop intersections (I have a bunch in my neighbourhood) and we can see at the gaz level go down rapidly.
Using premium, acceleration is easy and the rpm keeps lower, and the gaz gauge is more stable.
Not sure if the programming is exactly the same. You can see the RPM mapping between the engines is slightly different. The 2016 Toyota Tacoma, released in 2015, was the first Toyota vehicle to use the 2GR-FKS engine with the same C/R, and it's tuned to make 278/265.
Originally Posted by clwu
The GS 350 uses the SAME engine as the RX 350. GS 350 uses 91 Octane Premium and gets more HP and Torque. I think your will get the same performance if you put 91 octane in the RX 350.
Your new Lexus is delivered with regular gas and it will run just fine on it. At todays cost for Premium, I bet it sits in the station's underground tanks so long that you are not getting what you paid for.
Agreed, use the gas your car was designed for, simple as that.
I fill up at Costco so they circulate a lot of premium gas. I wonder if octane booster is added at the pump though - I can't imagine a fuel truck carrying separate compartments for Regular, Plus, and Premium.
it is compartmentalized -- they carry diesel in the same trucks, too. I drive a lot for work and have watched the trucks fill up the tank many times.
Originally Posted by ericsan13
Agreed, use the gas your car was designed for, simple as that.
I fill up at Costco so they circulate a lot of premium gas. I wonder if octane booster is added at the pump though - I can't imagine a fuel truck carrying separate compartments for Regular, Plus, and Premium.
My dad works as a manger for a fuel department and I didn't know this but there are only three tanks usually... 87 and 93/94 when you pick 91 it pulls from both of those tanks to make it 91. And a 3rd tank is used for diesel.
Done many mileage tests using both fuels, no difference. ....I have never noticed any appreciable difference in performance,...
I concur, I did the same - no difference, nothing that I could reliably repeat and brag about. I think for some it is a placebo effect. If there is some lab-measured difference it must be significantly less than price differential between both fuels.
Agreed, use the gas your car was designed for, simple as that.
I fill up at Costco so they circulate a lot of premium gas. I wonder if octane booster is added at the pump though - I can't imagine a fuel truck carrying separate compartments for Regular, Plus, and Premium.
At the Costco(s) I visit, there are only two grades available - regular and premium. There is zero chance of either of the two sitting in a tank for any length of time. If the positive benefits attributed to premium gas is a placebo effect, anyone familiar with medicine will tell you that a placebo effect is indeed a real effect. I think it may depend on the cost difference you encounter (at my Costco's, premium is often priced less than other stations regular), how much you drive, etc. Most of us paid a fair amount for our RX, if paying a little a little more works for you, I say 'go for it'.
