Recommended Gas

[dymmste]

I note that the spec calls for 91octane fuel, but all the gas stations (Shell and Chevron) around me sell what is claimed to be 87, 89 or 93 octane. Are people mixing 89 and 93 to get 91 or are the gas stations mis-representing the real ratings.
I expect to take deliver of my Elise very soon and do not want to make any stupid mistakes with the engine.
I remember from my Alfa a few years ago when i lived in Italy that it liked 'Plus' (91 I think) fuel but got a bit too hot running 'Super' (93).

Any thoughts from those already playing with their nice automotive toys would be most appreicated.

[Crash]

I believe the recommendation is for at least 91 octane. Isn't it?

[ChrisH]

Use 91 or better. The engine computer will adapt to the higher octane if over 91 (like 93), and can produce slightly better or smoother performance. Note that the ability of modern engines to adapt to the octane is different than the old rule of thumb of it being a waste to use an octane higher than recommended. This is because the ECU can now sense the residuals form the combustions, have knock sensors, and can adjust or retard the timing to adjust. Also, this is a high compression engine, which likes higher octanes.

[Karl_Ellzey]

So what would happen if you added some octane boost to your tank?