It may make you feel posh (or practical) to pull up to the pump and request premium unleaded for your tank, but chances are you're throwing away your hard-earned cash on an unnecessary type of gas. Per the American Automobile Association, US drivers blew about $2.1 billion on higher-octane fuel than their cars need, as most engines—about 70%—are sated with regular unleaded fuel, CNNMoney reports. AAA says despite this fact, about 16.5 million drivers admitted filling up at least once last year with the higher-grade gas, which costs, on average, about 50 cents more per gallon than regular. "Drivers see the 'premium' name at the pump and may assume the fuel is better for their vehicle," an AAA engineering and repair expert notes. High-octane fuel's benefits, per Edmunds.com: It's able to withstand more compression without combusting, making it critical in high-performance engines.
But while cars on the "premium required" list need that higher-grade fuel to prevent engine damage—about 16% of Americans drive those types of cars, per CNN—Edmunds notes cars on the "premium recommended" list are likely just fine with regular gas, thanks to advanced engine technology. The engine won't suffer, and the worst effect may be a slight speed reduction (e.g., a half-second when going from zero to 60mph). And while some drivers may still buy premium once in a while to flush out the tank, experts note all gas grades have an ample amount of additives for cutting down emissions and keeping engines in tiptop shape. What AAA says is a better bet, per MarketWatch: taking your car for regular maintenance checkups and keeping away from low-quality gas, which is different than regular gas from a top-tier brand. (The Southeast is enduring a gas-price spike.)