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Premium Gas

daihard

Ready to race!
Cars not tuned for higher octane fuel will see zero benefit from running it - performance and mileage will be the same (or possibly slightly worse, as higher octane fuel is tougher to ignite).

Cars tuned for higher octane fuel, like the GTI, will see both performance and quite possibly mileage increases, as they can run a leaner mixture without the danger of misfiring. A leaner mixture means less fuel in the fuel/air mix (or more air). I'm pretty sure you can see why it's quite possible to end up with better mileage! This is also why some with tunes have seen highway mileage creep up a bit - the APR/GIAC/Etc. tunes assume you're ALWAYS using 91 or 93, so they push the envelope a little further towards leaner mixtures (generally by pumping more air in from the turbo). They also monkey around with the timing to take advantage of the mixture, as well as a number of other variables. Not quite as safe, but you get way more power out of it and slightly better economy to boot.

As for the "why", basically, a leaner mixture is more prone to preignition/detonation, but it's also a more potent mixture. Running rich is safer, but causes more pollution (soot, mainly) and produces less power.

I understand what you're saying. I certainly appreciate all that information as technical details like that will always educate me.

Now do the hardware components play a big part there? For instance, you talk about air/fuel mixture, ignition timing, etc. Are they all controlled by software? If so, it should be able to adjust to the lower potential of regular gas without causing much (if at all) extra wear and tear to the engine, shouldn't it?

Now this may be off, but if using regular gas on the GTI were to be as much of a setback as you and Tailwagger explain (i.e. shorter engine life, more wear and tear, etc), would it really be wise for VW to simply state that premium gas is "recommended for maximum performance"? I would word it differently - such as "premium gas is strongly recommended for maximum performance, longer engine life and better fuel economy."
 

Darkmkvigti

Ready to race!
I did not realize this is an actual issue for people...the car requires premium gas SO DO IT.
Enough said, there should be no debate, if you don't want to put 91 or better go by a golf or a jetta...better yet a TDI.
 

daihard

Ready to race!
I did not realize this is an actual issue for people...the car requires premium gas SO DO IT.
Enough said, there should be no debate, if you don't want to put 91 or better go by a golf or a jetta...better yet a TDI.



Breaking news: the 2010 GTI does NOT require premium gas. :)
 

daihard

Ready to race!
To jmblur and Tailwagger:

Just to be sure, I do believe that if we knew the technical details you two have given to us, more people would decide to spend extra on premium gas or choose a car that's not designed for premium gas.
 

Antero128

Ready to race!
I'm not the one putting laughing smilies in my post. You also have no clue as to my financial situation do so please don't pass judgment on me. You are inferring things you have no clue about and frankly are none of your business.

I really dont care about your financial situation. I am just commenting on your posts. You are the one that is telling everybody that you dont want to spend the $3-5 a tank on premium fuel while driving a BMW.
 

daihard

Ready to race!
Understood...but the manual shows.

"Premium unleaded recommended for maximum performance"

Exactly! I was going to take out the owner's manual myself, but you saved my time. :)
 

Darkmkvigti

Ready to race!
I did not realize this is an actual issue for people...the car requires premium gas SO DO IT.
Enough said, there should be no debate, if you don't want to put 91 or better go by a golf or a jetta...better yet a TDI.

So once again, whats the issue. If the manufacture recommends premium then for GOD SAKES put in premium fuel.

If VW thought you could put less then they would have stated that. Obviously VW did some extensive R & D to conclude that premium is the best for everything to do with the TSI engine.
 

daihard

Ready to race!
So once again, whats the issue. If the manufacture recommends premium then for GOD SAKES put in premium fuel.
They recommend premium gas, instead of requiring it. :)

If VW thought you could put less then they would have stated that.
That's exactly what VW did. Their statement indicates that you can use regular gas if you don't need the maximum performance. And not everyone does. :)
 

jmblur1

Go Kart Champion
That's exactly what VW did. Their statement indicates that you can use regular gas if you don't need the maximum performance. And not everyone does. :)

And that's why they made Golf 2.5s.
 

jmblur1

Go Kart Champion
That's exactly what VW did. Their statement indicates that you can use regular gas if you don't need the maximum performance. And not everyone does. :)

And that's why they made Golf 2.5s.

Why spend another 5+ grand on a GTI if you're just going to hamstring its performance?
 

Darkmkvigti

Ready to race!
They recommend premium gas, instead of requiring it. :)


That's exactly what VW did. Their statement indicates that you can use regular gas if you don't need the maximum performance. And not everyone does. :)

If that is true I stand corrected.
But...who, where and when did you get that info, VW mechanics advised me only put in premium unless you leased the car, if so then who cares.
P.S Pls do not say that you got that info from a salesman, cause as we know...most of them could not tell the difference between there ass and there elbow.
 

daihard

Ready to race!
And that's why they made Golf 2.5s.

Why spend another 5+ grand on a GTI if you're just going to hamstring its performance?

I am pretty sure the GTI fed with regular gas would still perform better than the Golf 2.5, though I'm not one to test with my own car. :)

In case I was not clear, I would never put regular gas in my GTI. Like I said again and again, I just don't think it's right to pass that judgment onto others that I only know through this forum. I find it totally understandable that people say "I would not recommend using regular fuel on the GTI because..." OTOH, I see posters after posters stating their opinions on this as if they were the absolute truth that everyone *must* follow or they are insane. That's what I do not really like.

Am I really being too unreasonable here?
 

jmblur1

Go Kart Champion
Am I really being too unreasonable here?

Yup. If we were telling people they MUST buy the GTI, then you have a legitimate point - not everybody needs the performance. But unless you're in dire straights (and don't get your money for nothing and your chicks for free :lol:) it makes no sense to feed your performance car lesser fuel to save what amounts to pocket change.

Now, if premium fuel was a buck+ more a gallon, THEN you might have a point... but $3 a fill-up? If you're THAT tight on money, take the bus!
 
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