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Discussion Starter #1 (Edited)
******************Not another EV thread*****************Not another EV thread********************

I dare put in 87 octane in my Mercedes...that's for sho' :p



In a study that could indicate a need to change how we name fuels, the American Automobile Association (AAA) discovered that using premium fuel (91-93 octane) in a car that only requires regular (87 octane) does absolutely nothing. AAA's experiment looked at whether cars requiring just regular fuel would have an effect on power, fuel economy, and emissions. To do this, they used 2016 models of a V8 Toyota Tundra, V6 Dodge Charger, and 2.0-liter Mazda 3. Each car was put through the EPA's city, highway and aggressive driving loops on a chassis dyno, with only the fuel as a variable. The testers also did horsepower measurements on the dyno.

In the end, every aspect remained virtually the same. There were minute changes for some of the vehicles, but they weren't enough to be noticeable. And for fuel economy, the differences wouldn't even come close to the 23-percent increase in fuel cost AAA estimated for premium. AAA director of automotive engineering Greg Brannon said that the cars did recognize and compensate for the different octane fuels. AAA measured ignition timing in each vehicle with each type of fuel, and there was a noticeable change in timing when premium fuel was used. So it was surprising to the testers that none of the vehicles adjusted timing in such a way that would improve at least one performance aspect. In essence, Americans waste $2.1 billion every single year on premium gas that their cars don't need, AAA says.

There is one minor caveat to this test though. The only thing tested here was the effect of octane on vehicle performance. While spending more on premium won't get you any benefits, there are differences in fuels, but the differences come from fuel quality, not octane. In a test done by AAA earlier this year, it was discovered that fuel that meets TOP TIER standards for fuel detergents and additives are much better for engines. The test revealed that fuel that only meets government requirements for additives left 19 percent more deposits over 4,000 miles compared with the TOP TIER fuel. If you're interested in which brands sell TOP TIER fuel, you can find the list here. So the takeaway here is buy the fuel the manufacturer recommends, and buy it from a TOP TIER brand. This way you'll save money and keep your car healthy.
http://www.autoblog.com/2016/09/20/premium-fuel-aaa-study/

 

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I thought there would be more people putting 87 into cars requiring 91 than the other way around.
 

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I believe it. My wife's wk2 GC recommends we use 89 octane, but all gas stations in my area only have 87, 91 and 93. In the manual it clearly states not to use anything higher than 89, as it provides no additional benefit so we just always use 87, as the manual says is an acceptable alternative, although engine performance will be reduced. Its fine, as my wife won't know the difference
 

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Discussion Starter #4
AAA's experiment looked at whether cars requiring just regular fuel would have an effect on power, fuel economy, and emissions. To do this, they used 2016 models of a V8 Toyota Tundra, V6 Dodge Charger, and 2.0-liter Mazda 3.
Am I the only one that's noticed that these cars do not take Premium fuel anyway? :D
 

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Yes, if you're doing it just for the octane, I'd agree. Many people, myself included, do it to escape the Ethanol. Corn should grown be for eating.
 

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They need to do a report on how much Americans waste on AAA memberships.
 

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Am I the only one that's noticed that these cars do not take Premium fuel anyway? :D
yeah, i think that's the point. although i do wonder how they come to the $2.1 billion figure given that some cars do require premium and it isn't as if AAA would know who is filling up with what. I find it difficult to believe that the vast majority of people would willingly pay for more expensive gas, especially when I see people waiting 10+ minutes just to fill up at stations with cheaper prices. Also, as someone already mentioned, their estimate doesn't take into account the people who don't put in premium even when their vehicle requires it (such as my dad). :banghead:
 

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Discussion Starter #10
Wasnt that the point of this "study"? To see what effects (if any) there were of using premium fuel in a vehicle that does not require it...
That's my point. Why not use 2016 Porsche Boxter for this study. Or even a VW GTI that "requires" premium fuel. Unless VW GTI isn't a performance car. :p Does Charger SRT8 take regular or premium?

Oh I forgot...it's AAA. :D
 

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Am I the only one that's noticed that these cars do not take Premium fuel anyway? :D
That's the point. Some people put premium in cars that do not recommend premium, which is a waste of money based on a superstition that premium means it is better and makes your car automatically run better.
 

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Discussion Starter #14
That's the point. Some people put premium in cars that do not recommend premium, which is a waste of money based on a superstition that premium means it is better and makes your car automatically run better.
:D I was trying to be nice. I'm sure some TCLer is putting premium gas in his (or hers) Mitsubishi Galant right now.
 

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A friend only puts premium in his SX4. Exactly why ... I dunno.

The truck calls for 89 - but since Costco premium is so cheap (42.09 this morning) that's what it gets.
 

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OK, so the test was to see if a higher octane fuel had any benefit on vehicles that didn't require it. I get it, there's not much of a surprise there.

How did they know which 87 octane owners were using premium, and how much they were using? Is that where they are suggesting the $2.1B is going?

....either that or they assumed that since their test cars didn't benefit, that the cars that require it don't benefit either, and the $2.1B figure was ALL premium sold in the US.

Am I right, or was this deduction based on 14 year old logic?
 

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I honestly thought it was general knowledge by now that using a higher octane fuel than what is actually required isn't going to increase performance or fuel economy.

The more useful test really is seeing what effect using a lower than required octane fuel has to your car.
 

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There is no difference most of the year, but in the dog days of summer when it's regularly over 100° I put 89 octane in my car and it is noticeably happier. The average person just cruising along who never exceeds 3000 RPM would probably never notice a difference, but mine sees the upper end of the tachometer multiple times a day and the full travel of the accelerator is used frequently.

It has always pulled timing (feels like very slight bucking or hesitation) if it is very hot and I give it a lot of gas at low revs. An example would be if I am coasting up to a red light in 2nd at 10 MPH, then floor it when it turns green. Running midgrade it will just go and pull away smoothly, but if I have 87 in it it will hesitate very slightly while starting to accelerate.

Similarly, it feels kind of sluggish in a WOT situation when it is very hot, like winding 2nd out to 60 MPH up a merge ramp into fast traffic. It revs reluctantly and unenthusiastically but with 89 it just feels normal and pulls smoothly/quickly up to 6500.

I guess it is pinging ever so slightly and the computer is retarding things when it is running 87. Also, with only 105 hp on tap, it is pretty noticeable when it is down on power. Not sure a slight power drop on a V6 Dodge or V8 Tundra would be as noticeable proportionally.
 

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Discussion Starter #19
The more useful test really is seeing what effect using a lower than required octane fuel has to your car.
I heard somewhere that another organization will try that route:



:D
 

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Who put 91+ octane in a car that requires only 87? Never heard of that happening. Usually people complain about the need to use high octane fuel.

I put the highest octane fuel I can reasonably find in both of my cars because they are generally designed for it and run better on it. In the SO's tucson, it's strictly 87.
 
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