20 years ago I bought an Alfa that was supposed to use premium. It had Bosch electronic fuel injection and my understanding was that even at that time, the sensors would adjust to the fuel. So, I put mid grade gas in and it ran fine, except that it had a tiny bit less power and got about 10% less mpg. So, I did the math and found that miles per dollar worked out about the same for mid and premium. I stayed with premium for the extra performance. The stock 1987 Alfalfa Spyders were not to quick to begin with, but what an absolute great, fun car to drive.

So, I did the same test with my CX-7 and found that there was no noticeable mileage or performance difference between premiium and mid grade. I also believe that the octane difference between now and 20 years ago was greater for the two grades of gas. The only recent car I had that knocked with mid grade was my 95 BMW 530i stick. I loved that car, but got to meet too many men driving black and white cars.

Any of you cheating on the gas grade too?

Any of you try regular?

 

This is not a matter of sensors.

You have both very high compression plus very high boost to obtain the power levels of this engine. To use a lower grade of gas will allow the fuel to detonate instead of burn. This in turn will damage your engine. Think hand granade vs a flame.

The computers will try to save your engine by killing boost and retarding the timing etc but it can only do so much.

Do this at your own risk. Not worth totalling your engine to save $5.00 a fill up.