Nice breakdown B5.

I agree and while my examples aren't from Audi/VW products I do have two experiences both from my parents who want a nice car but are too cheap to actually use the proper gas.

First vehicle was a new 2000 Infiniti I30 that my mother had. She drives rather hard and that car only "recommended" 91 octane and technically didn't require it, but the manual suggested that you use it unless you were driving more gently and keeping the car below highway speeds.

They never put a drop of 91 octane in the car and by 35,000 miles the car ticked and knocked regularly and by 50,000 miles they had blown all 6 coil packs in the engine.

Next vehicle was a 2006 Lexus ES330. This one required 91 octane and still they put in 87 each and every time. No coil packs were blown, but ever since that car had hit about 30,000 miles its ticked horribly at idle and has a lot of chatter during moderate acceleration.

Long story short, the 20 cents extra a gallon is hardly noticeable on your overall fill up, it nets you worse fuel economy and potentially costs you more in mileage alone, and despite knock sensors which may help in the short term, its not good for your car.

Knock sensors are designed to prevent issues in the event that you can't get the proper grade of fuel. Its not supposed to be there as a save all so that you can run a lower grade of gasoline for the life of the car.

 

Looking at the math helps a lot, but i'm curious where did you get 3-4mpg from??

 

I think it was expected from the way the knock sensor would work but not confirmed.

Going the opposite direction, has anyone used E85 yet? The 2013s are supposed to be able to take it and it does give the driver higher octane (105). Does the car make use of the higher octane or do you just end up using funny fuel that costs more?

(E85 has a lower energy density than 87/91 octane, so mpg is about 3/4ths and only comes ahead if ethanol gets really cheap compared to gasoline).

 

Forget the math, forget the "science" and debates on 87 vs. 91 or 93....

If $2- $3 extra on a $40- $50 fill up is too much, Audi is not the car for you.

Period.

 

I've had some experience with the 1.8T and 2.0T. And I used the internet to look up averages. I used the lower number as a baseline.

 

Good well written info, read and heed. Pay now or pay later.

 

Exactly. Sad thing is though. I'm going to bet that they will still put 87 in. Those poor poor cars....

 

Interesting topic....who drives at altitude?...I am at 5500' above sea level, whereas many of you are probably much lower. How does higher altitudes versus octane variances work pro or con with 91 vs 87?

 

These are forced induction engines. With a forced induction engine altitude isn't an issue. On a N/A engine though, it's another story.

 

That would be true...thank you