Chances are, the label inside your fuel compartment or cap has a recommended gas octane value recommended. The fuel octane levels start at 87 (regular), then to 88–90 (midgrade), and finally 91–94 (premium). If you’re driving a standard mid-size sedan, you’re most likely to have a fuel octane recommended value of 87. If you’re driving a premium sedan, then you’re more likely to have a recommended octane value of 91+. If you have particularly owned a premium sedan, I'm sure you’ve asked yourself the question: Is it really worth it?
A study was done to try and answer this question. Six vehicles were tested using a dyno setup and the results were surprising. Similarly in all six vehicles, it was found that there was a minor increase in performance and decrease in fuel consumption BUT, the study concluded that the minor increase in performance and fuel economy increase did not outweigh the extra cost you would be paying at the pump. This may lead to your next question: is using regular octane fuel in my premium octane fuel recommended vehicle going to cause any damage?
In today’s intelligent vehicles, even though there is a recommended octane level, the cars are programmed to adapt to the lower sensed octane levels without the car owners interference. The higher octane level reduces to minimum engine knock. But in today’s cars, the intelligent engine control systems are able to automatically compensate for the low octane fuel by adjusting ignition timing. This very sophisticated electronic capability effectively automatically tunes engines on the fly and gives drivers much more flexibility in the octane grade of fuel that they can use safely.