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On my wife's Lexus (Toyota 3.5L V6) it's specified to run on 87 octane, but I swear every time I've filled with 87 the car ended up feeling sluggish, like the throttle response was somehow muted a bit more. Now that I picked up a Jeep with the 3.6 Pentastar rated for 87 octane, I'm wondering the same thing. I totally get that they're probably programmed to run acceptably on 87 octane, but do things like throttle response possibly get adjusted if higher octane gas is used? I know Mazda specifically advertises two different HP ratings for some of their engines, acknowledging that you can run 87 no problem, but that the ECU will dial up/down based on what's in the tank. I'm wondering if other manufactures do this but just don't communicate it.

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It's hard to paint a broad brush stroke because each manufacturer takes a different approach. I will say that it's more common than not to have a laggy throttle response due to emissions/economy tunes that most manufacturers will use as the default setting. The throttle opening is almost never linear to a pedal command in a modern DBW system because it's tuned that way. That's why some manufacturers build in 'Sport' modes that sharpen throttle response greatly, and why 3rd party devices such as Pedal Commander exist.
 

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My GX470 recommends 93 but can run 87 without issue. However, it gets worse mileage on 87 in addition to making less power, so the real world savings from running cheaper gas are pretty minimal.
 

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I feel like it's the other way around for most cars. Like, they can run fine on 87 the majority of the time (that is the "high" HP rating) but can dial it back to an unspecified number if there is any pinging/detonation/etc. I don't feel like any cars that specify 87 will uncork extra power by using midgrade or premium, they might just not retard the timing as much in harsh conditions. In effect, using 89 keeps the power at the base level even when it's super hot.

For example, when I commuted in the Yaris, I would put 89 in it in the dog days of summer because it would pull timing/hesitate a little if I gave it a lot of gas at low revs when it was 105° and heat soaked in traffic (like if I was coasting up to a light at 10 MPH in 2nd, the light turns green and I floor it). It also revved with a lot less verve and pulled reluctantly, instead of enthusiastically through the gears. I don't notice a change in some cars, but my old Civic Si also felt like that where it would hesitate if I gave it a lot of gas at low revs when it was super hot. On 89 both cars are/were a lot peppier in the summer. The rest of the year they get/got 87.

For the average person who never goes over 2500 RPM, 87 probably fine, even if the car requires premium. But if you rip on it a lot, take it to the redline frequently or live where it goes over 100° a lot, it's worth going up to at least midgrade in certain circumstances, or at least experimenting with it to see if the car reacts positively.
 

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For years, the TSI Volkswagens all required 91 minimum, and suddenly it is 87 with the gen3 engine. I feel that this is really just a response to the market; someone buying a Passat or Tiguan was annoyed that they had to use more expensive gas on their commute. With modern ECUs, it's easy for computer to instantly respond to sensor data to protect the motor, so it's not like low octane gas is gonna cause a turbo motor to destroy itself anymore. However, I also suspect that the automotive industry constantly pointing out the VW under reports it's performance numbers is probably based on reviewers putting in 91-93 like they always have, and suddenly it's making 10hp and 20lb/ft more.

Honestly, the biggest annoyance for me for years about 91 octane was how it's not really available around me. 87, 89, and then the big jump to 93. I have NEVER seen a car that requires 89.
 

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I don't feel like any cars that specify 87 will uncork extra power by using midgrade or
The Ranger specifically calls out two power levels in the manual. It states 87 octane is acceptable but if additional performance is desired, 93 is recommended. This was all but confirmed when Ford announced the Ranger was rated at 270hp specifically on 87, and Dyno testing has repeatedly found the difference between 87 and 93 is around 30hp.
I can also confirm, the truck is noticably faster on premium.
 
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The Ranger specifically calls out two power levels in the manual. It states 87 octane is acceptable but if additional performance is desired, 93 is recommended. This was all but confirmed when Ford announced the Ranger was rated at 270hp specifically on 87, and Dyno testing has repeatedly found the difference between 87 and 93 is around 30hp.
I can also confirm, the truck is noticably faster on premium.
Yeah, turbo DI engines are a different animal. I meant ones like my iron block boat anchor, the ancient Yaris engine, etc. where the manual recommends "87" with no verbiage about additional performance. High test might not add any power but it can keep the ECU from retarding timing as much.
 

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Fairly certain the Mazda hp gains on 93 is because turbo + DI. NA engines normally only require 87 with no real benefits with 93.

Using a top tier fuel is more important than throwing 93 at a 87 rated application.
 

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The Miata is NA, but wildly high compression (14:1 if memory serves). So, I can totally see 93 being a benefit with those motors.
I'm referring to the image the OP posted. This is a 2.5 Skyactive Turbo:

https://www.vwvortex.com/cdn-cgi/image/format=auto,********redirect,width=1920,height=1920,fit=scale-down/https://www.vwvortex.com/attachments/screenshot-2022-06-22-101616-png.196857/
 

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For years, the TSI Volkswagens all required 91 minimum, and suddenly it is 87 with the gen3 engine. I feel that this is really just a response to the market; someone buying a Passat or Tiguan was annoyed that they had to use more expensive gas on their commute. With modern ECUs, it's easy for computer to instantly respond to sensor data to protect the motor, so it's not like low octane gas is gonna cause a turbo motor to destroy itself anymore. However, I also suspect that the automotive industry constantly pointing out the VW under reports it's performance numbers is probably based on reviewers putting in 91-93 like they always have, and suddenly it's making 10hp and 20lb/ft more.

Honestly, the biggest annoyance for me for years about 91 octane was how it's not really available around me. 87, 89, and then the big jump to 93. I have NEVER seen a car that requires 89.
I always put 93 in the GTI and did in the Elantra Sport. Both turbo DI engines.

Is it a waste? Meh, rather keep the performance consistent than cheap out with the minimum. It's a few bucks difference, big deal.
 

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Ford specifically states to use premium for the Maverick when towing/at elevation.
 

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I think a lot of it depends on how sensitive you are to changes, too. I notice lots of things that many people say "there's no difference" about. Including how cars run on 87 vs. 91. Even my 4.0 4Runner ran better on premium; would it drive on 85? Absolutely. Did it pull timing on those hot days up at 7,000 feet? You betcha.

On my Outback, which has the turbo 2.4, the difference is even more noticeable. I do believe most modern turbo motors have a lot of on-the-fly computer trickery adapting to the fuel they detect. And, of course, higher temps or higher elevation exacerbate the differences. YMMV.
 

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I live in Denver and daily drive a MkVI GTI and regularly am up at high elevation. With prices the way have been, 85 is $4.89 and 91 is $5.59. I have occasionally put 85 in the car as it's nearly an $8 price difference and for someone who drives quite a bit, that savings can add up. But I can say from personal experience, the difference in the responsiveness of the car is quite noticeable. Sitting in traffic on a hot day with the AC on the car feels much more sluggish and slow to respond. I strangely didn't notice much of a difference at all in MPG.
 
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