If I see both 91 and 93, should I choose 91?

 

The difference is probably neglible, especially if the car is tuned for 91. Is there a price difference? If not, go with whatever floats your boat.

 

I put 93, but then there is no 91 around here. The car should adapt itself to whatever gas, and it seems to mean that there should be a tiny boost with 93 as opposed to 91, but it is probably very small. If I had to choose, I'd still put 93, but that's just me.

 

I don't know about 91 but the difference between 93 and 87 in this car is very noticeable. It will take 87 fine but it LOVES 93.