Premium-grade gas can cost as much as $1,00 more per gallon than regular, yet some "regular" cars now require it to achieve their full performance potential

For years, car care experts have been advising motorists not to spend the extra money for 91-octane premium-grade gasoline unless it’s specifically required by the automaker, usually for higher performance models. If your vehicle runs perfectly fine on 89-octane regular-grade fuel, filling the tank with premium is just a waste of money as the higher rating will do nothing to improve its performance.

That’s the conventional wisdom, but today’s precisely engineered cars with their higher-compression turbocharged and direct fuel-injected engines are increasingly recommending the use of 91-octane premium-grade fuel to achieve their maximum performance potential, and that includes a surprising number of otherwise “regular” vehicles like certain versions of the Chevrolet Malibu sedan and the Jeep Renegade crossover SUV. This can effectively boost a given model’s operating costs by anywhere between 50 cents and a buck per gallon, depending on where one lives. That can add up to an extra $1,000-$2,500 spent over a five-year period.

We’re highlighting 15 cars for 2018 you might not expect to prefer riding on premium-grade gasoline in the accompanying slideshow.

Fuel requirements for a given model are printed on a label that’s affixed to the inside of the fuel filler door and are noted in the vehicle’s owner’s manual; this information is also available along with a vehicle’s fuel economy ratings at the Environmental Protection Agency’s website, ww.fueleconomy.gov. While today’s engines include a so-called knock sensor that can automatically alter the timing of the spark plugs to safely accommodate lower octane fuel than is otherwise recommended, your car’s performance and its fuel economy will be adversely affected to some degree if you’re running it on regular when premium-grade is otherwise recommended or required.

Helping you make the hard choices: