michael

I have been searching for the highest octane and have only found 94 RON from Exxon.<br>I thought I saw 98 somewhere but have checked all of the major suppliers with no luck. <br>Anyone notice any difference in performance from tank to tank?

Ray

My sales rep (who is also an automotive consultant and perhaps the largest private collector of auto books) discussed this topic with me a bit as they were prepping my car. He says Sunoco has the highest octane in the US, period. They also evidently own a high percentage of gasoline patents, but I can't confirm this.<p>I was told that the average driver wouldn't be able to tell the difference between the best grades of Sunoco and any other high-quality supplier. But you would notice the difference between premium and lower grades - you'd get a 6-8hp improvement as well as better mileage, etc.

JMaTT

Question: Does the TT have engine knock sensors that automatically retard the timing &/or decrease the boost if knock is detected?<p>If it does, then get the highest octane you can find. If you really want performance once in a while, there are various octane boosters that can be added to your fuel. They are available at most car parts stores.<p>If the TT doesn't have knock sensors, then buy the cheapest gasoline you can find that still won't knock under HARD acceleration. Any octane higher than that is wasted money.<p>If there are any SAE types on the board, maybe they could post the tech info behind this.

JMaTT

I did some more research. The TT indeed has knock sensors (I thought so, but wasn't positive). I would buy the best fuel you can, AND add some octane booster once in a while if you can feel a difference. All octane does, is prevent pre-ignition (knock) in the cylinders. After a certain point, based on the TT's engine management, excess octane won't do anything for you. But based on the TT's system, your car may run fine on 89 octane, but feel a lot more powerful at 95 or 100+. Let me know any results.<br>

STTeve R

I was told that for city driving even regular unleaded gas will work. It will lessen quick responses but if you are in stop and go for 30 minutes daily or so, why bother paying the extra? The sensors will adjust for the lower octane.<br>For freeway/highway driving, the best is the recommended high test (high octane). Sunoco DOES provide the best but unfortunately not everyone can get their hands on it.