I know this has been debated many times as I did read on the forum but I still didn't get an answer. I am interested in knowing the facts, what do we know and what are we uncertain about.

Getting my car from the dealer, my sales manger told me that you could use the medium grade fuel (. I think this is what they filled my car with when buying it because the fuel ran out so fast (or maybe I was driving hard ).

After that I put Shell's Vpower nitro+ (93/94 octane?)
This week I used Petro ultra 94 (Should I just have went Petro 91 ?)

Petro I get points, Shell I would get Airmiles. I believe Shell's has no ethanol as I read on the pump but doesn't regulations state 10% ethanol required?

Does it even matter ? Should I just fill where it is cheaper?

 

Follow the fuel recommendations in your owners manual. Millions of dollars went into engineering this car so there are valid reasons for using the correct octane.

 

Realistically, you could use even the lowest grade fuel in the car as the ECU has parameters to detect low octane fuel and compensate for it. Now what happens when you put in a tank of low octane fuel?

1. The ECU essentially thinks you have a tank of bad gas and pulls ignition timing to prevent any detonation/ping
2. This timing retardation means your engine is no longer running to optimal conditions within its design, reducing overall efficiency
3. You risk premature wear on your entire fuel system (fuel pump, fuel lines, fuel injectors, etc)

Here in Southern California, the difference between the lowest grade fuel (87 Octane) and the highest grade fuel (91 Octane) over the course of one fill up will amount to no more than $3.00. Is this small amount of money over each fill up worth the potential negative side effects to your vehicle?

Side note: almost every fuel station here in SoCal has a disclaimer printed at the pumps which says (Up to 10% Ethanol content). In my time of ownership, I have never ran into any problems where the fuel in my tank is a culprit!

 

Based on my individual experience my supercharged V8 runs best on non_ethonal 91 octane. That is only from personal observation, no facts.

 

I found short shifting with the paddles and letting the car down shift will help with consumption a little bit. No sense in shifting at 3000 rpm if you can shift at 1500 this car has more then enough torque to handle low rpm short shifts. With that said I wish I could change the minimum RPM shift point to less than 1000.