2026 Lexus NX 350h F SportNATHAN LEACH-PROFFEREveryone knows premium gas is more expensive than regular, sometimes a lot more. But most people usually ask themselves: "Does this give me better mileage or make my vehicle run more smoothly?"The answer, according to a new Consumer Reports study, is no.Using two luxury SUVs from the same brand, Consumer Reports testing found virtually no measurable difference in acceleration or fuel economy when using require premium gas or regular 87 octane fuel.SUVs that requires premium gas can cost more than $3,000 in extra fuel costs over five years of ownership due to the price gap between octane grades. Automakers often push premium gas requirements to achieve higher performance specs that the average driver might not notice.Recommendation - use premium if guidelines say premiumEven cars that don't require premium can confuse drivers with unclear fuel guidelines in owner's manuals. If your car requires premium, use premium, says CD. But if it only recommends premium, it's safe to use regular in most scenarios.The Lexus TX's owner's manual, for example, warns that using fuel rated at less than 91 octane may void the vehicle warranty. A Lexus spokesperson told CR that its engines are "tuned for slightly more power and refinement characteristics and require 91 octane fuel."But when Consumer Reports tested acceleration and fuel economy, it found no meaningful performance difference between the Lexus and Toyota SUVs. Another Lexus/Toyota comparison produced essentially the same result."In our testing, we couldn't quantify additional 'performance or refinement' from the premium versions of the engines that we compared," said Jake Fisher, senior director of Consumer Reports' Auto Test Center. "But the average consumer will notice the hundreds more they'll be spending on fuel every year."It's not just LexusCR says its analysis found more than 30 recently tested vehicles that either explicitly require premium fuel or place such tight restrictions on using regular that premium is effectively required.Many more vehicles only recommend premium, but the wording can be confusing enough that drivers may not realize regular fuel is acceptable, potentially saving thousands per year.Only a small number of those vehicles are true sports cars, such as the Chevrolet Corvette, where premium can be necessary because of the additional stress and heat created during high-performance driving.But many of the others are luxury SUVs from manufacturers including Audi and Volvo, vehicles far more likely to spend their lives commuting and running errands than circulating a racetrack."A handful of high-performance vehicles truly benefit from premium, but some automakers are using premium fuel to squeeze extra horsepower out of family haulers," says Fisher. "It's often for bragging rights rather than any consumer benefit."The premium requirement can be especially important for shoppers considering used luxury cars. Those vehicles can look like bargains because depreciation may leave buyers with more features for less money than a comparable new mainstream model. But the savings can shrink once operating costs are considered. Premium gasoline costs about 25 percent more than regular on average.With fuel prices staying high, Consumer Reports argues that automakers should avoid requiring premium unless there is a genuine need for it in a specialized vehicle. It also says manufacturers should make their fuel requirements much easier for owners to understand.The full report can be seen here.