I do notice a small difference in engine performance between the 91 octane that I normally put in my 2019 370Z with 12,000 miles and a 93 octane mixture from Sunoco SS 100 race gas and 91 octane pump gas. When I run the 93 octane blended mixture I notice that the engine idles a little more smoothly and more quietly and pulls a little more strongly from a start. With the 91 octane I sometimes get a little pinging and hesitation from a start if I don't feather the clutch correctly, none of that with the 93 octane. The most objective difference that I notice is in my longer term gas mileage indicator, where I get about a 2 mpg increase in mileage with the higher octane. The Sunoco race gas is hard to get here in Northern California and it is expensive, so I normally don't use it. My car's engine and exhaust system are still stock
