GTi Fuel

[FamilyDub]

^^^ Backing up Alan on this one. Talked to death elsewhere, though.

MKV: designed to run on 98+, will be ok on 95.
MKVI: designed to run on 95, better fuel will give decent gains, compared to MKV.

The FSI tech post would have been posted by ub7rm, maybe?

[Egbutt Wash]

What I do notice is that Morrisons petrol gives worse mpg than ordinary Shell.

[ub7rm]

^^^ Backing up Alan on this one. Talked to death elsewhere, though.

MKV: designed to run on 98+, will be ok on 95.
MKVI: designed to run on 95, better fuel will give decent gains, compared to MKV.

The FSI tech post would have been posted by ub7rm, maybe?

As you wish sir 

Regards FSI owners mainly.

The higher the octane rating of the fuel the longer the FSI engine will run in FSI mode.

You see, when the FSI is running in 'Fuel Stratified Injection' mode it creates a lot of NoX (NoX - Very bad as far as emisions go) due to it being such a lean burn, so it has a NoX Cat which abrorbs the NoX, once its full the Nox probe (fancy lambda probe) senses this and the engine switches back to normal running and can safely clear the NoX out with the other gases through the main Cat so it can switch back into in FSI mode again.

The problem with octane levels is, and this is just an example depending on driving styles.

Out of 100 miles average :-

95RON - 90 miles normal, 10 miles FSI (lots of NoX made in FSI mode)

97+RON - 60 miles normal, 40 miles FSI (some NoX made in FSI mode)

Now regardless of what anyone says this is how the engine is built and as its more efficient in FSI mode VW always recommend the highest octane rating for this reason, they did introduce a 1.4FSI for the uk market that is made to run on 95RON fuel for longer but you want to see the size of the NoX Cat, more like a tanker. lol

And after all that, you will get better miles to the gallon running 97+RON regardless of it being an FSI, its they way they are made these days, the ecu recognises when the fuel mixture combusts and will adjust it accordingly, the cheaper the fuel the more retarded the timing, the more retarded the timing the less power, the less power the more you 'need' to put the foot down.

Its part of the GTI hints and tricks thread in the maintenance section ...

[ub7rm]

What I do notice is that Morrisons petrol gives worse mpg than ordinary Shell.

I believe Morrisons fuel contains more biofuel than most other petrol ...

[Egbutt Wash]

What I do find is when I have a full tank of 99 my mpg drops.  Because I drive hell for leather to get my monies worth out of the dear stuff.  I even use the flapsters.

[FamilyDub]

The FSI tech post would have been posted by ub7rm, maybe?

As you wish sir 

 

What I do find is when I have a full tank of 99 my mpg drops. 

^^^ I notice a performance differential, but no gain/loss in mpg from either.

Although to be fair, my mileage/use is random and erratic, so I wouldn't like to be a test bed...

...unless someone is willing to pay for ten tanks of 99 and ten tanks of 95 to compare...   

[AlanD]

Whats you account name, sort code, account number etc and I'll send the monies over . . . .

[marty341]

Markv gtis are superb cars! look after it, and it will look after you

We all know which it prefers!? V-Power/Tesco Super all day long.

[scotland67]

According to the VW GTI Brochure, page 24, technical notes, 04, "Thanks to the knock control,unleaded four star(at least 95 ron) can be used instead of unleaded super plus"

[FamilyDub]

According to the VW GTI Brochure, page 24, technical notes, 04, "Thanks to the knock control,unleaded four star(at least 95 ron) can be used instead of unleaded super plus"

^^^ which brochure?