Why does a person buy more expensive high-octane gas for a vehicle that doesn't need it? It just seems to run better on high test, is the most common answer. It's better for the car.

Automotive engineers maintain than an engine designed to run on regular (87 octane) ought to run well on that fuel. The main reason for resorting to higher octane is because the engine was designed for that fuel; in this case it would be specified in the owner's manual. Another reason is if the car has been neglected and runs poorly in the standard grade of gas.

If your engine is getting hard to start, knocks or pings on hills, keeps running after the ignition is shut off (that's called "dieseling") or if it runs rough, upgrading the gas may help temporarily. But that inexpensive fix eventually will lead to real world engine services. Ask our service technicians what's causing the symptoms and take corrective measures.