There are owner's manuals for several cars that recommend that you use premium fuel, but a recent study from the American Automobile Association indicates that it might not be worth it.
The study was conducted to discover whether premium fuel yields improved fuel economy, more horsepower, and if it costs more. The vehicles used for the study were a Ford Mustang GT, Jeep Renegade, Mazda Miata, Cadillac Escalade ESV, Audi A3 and Ford F150 XLT EcoBoost.
The Escalade and Ford F150 EcoBoost saw the biggest benefits in regards to fuel economy, and the F150 also gained 11 horsepower.
Jalopnik explained how the scientists tested the cars to get the results, and each car was tested using the same method.
"To come up with answers, scientists strapped those six cars to chassis dynamometers, and ran various drive cycles that simulated ever-steeper grades (zero, two, 4 percent at 65 mph and 6 percent at 55 mph) in order to see if the benefits of premium fuel shined through during high-load driving conditions. The team then measured static (at 2,000 rpm and 4,000 rpm) and dynamic horsepower (the engine revs to redline like a normal dyno test) to see how premium fuel affects engine output."
Overall, the study deemed that paying the extra 20-25 cents in extra fuel than you'd normally pay for regular isn't exactly worth it.
"There is not a clear case where premium gasoline is beneficial from a cost perspective. In most cases, the extra cost of premium over regular does not result in a positive return on investment (lower cost to drive a given distance). However, there are instances - and they vary widely by vehicle type and model - where the use of premium gasoline can be marginally beneficial."
It's probably a good idea to test it out on your own to see if it's worth it for your car. Most cars don't recommend using premium fuel, but if yours does, try testing it out to see if it's really necessary.
Otherwise, you're just spending a lot more money than you need to be for gas. Unless you do a lot of towing or heavy-duty lifting, you're probably safe using regular fuel.