A person filling up a car with gas at a gas station. - Irene Miller/ShutterstockWe live in an era where fuel costs are steep, the cost of living crisis looms large, and within that context, saving a few bucks here and there can add up to something meaningful. Besides fuel, cars are also getting more expensive — the average new car price hit over $50,000 last year, more than double what it cost in 2000.Naturally, people go looking for tips — and the internet is happy to oblige, mostly with nonsense. Some of the most widely shared fuel-saving advice is not just ineffective, it actively works against you. Take coasting downhill in neutral: it feels intuitive, like you're letting the car roll for free.In reality, dropping into neutral forces the engine to maintain idle RPM to keep running, which means it's actively burning fuel. Leave it in gear and lift off the throttle, and modern fuel injection systems cut fuel delivery entirely — zero consumption until you need to brake or accelerate again. Neutral coasting doesn't save fuel. In the right conditions, it actually burns more.AdvertisementAdvertisementThat's just one example. Other myths include using premium fuel in a regular engine, warming up the engine before driving, always cutting the AC, consistently operating within cruise control, and accelerating as slowly as possible. Here's what's actually going on, and what you need to do to save fuel instead of wasting it.Read more: When (And Why) Did Cars Switch From Leaded To Unleaded Fuel?Myths surrounding high octane fuel usage, pre-warming an engine, and AC consumptionA close-up of a "MAX A/C" button engaged on a BMW climate system. - Kenneth Cheung/Getty ImagesRegarding when you should (and shouldn't) use premium gas in your car, running premium fuel in a regular engine is one of the most persistent money-saving tips myths. Premium has a higher octane rating, which resists pre-ignition in high-compression engines tuned to use it. In a regular engine, that property goes completely to waste. Even the EPA notes that for cars where premium is recommended but not required, "The cost increase is typically higher than the fuel savings."Warming up the engine before driving is another one. It made sense in the era of carburetors, but modern fuel-injected engines reach operating temperature faster by actually driving them gently. Idling in your driveway for five minutes isn't protecting your engine — it's just burning fuel while going nowhere. The windows down versus AC debate is more nuanced than people think.AdvertisementAdvertisementAt low speeds around town, yes — cutting the AC and opening the windows saves fuel. But at highway speeds, the aerodynamic drag created by open windows can offset or even exceed the fuel cost of running the AC. Therefore, if you want to save fuel when cruising on the highway, turn on the AC; when driving through the city, open a window.Turning the AC off completely seems like an obvious win, but how you use it matters more than whether it's on or off. Under very hot conditions, AC can reduce a conventional vehicle's fuel economy by more than 25%, especially during short outings. As a general rule of thumb, set the temperature to what you actually need, not as low as it goes, and the fuel penalty drops. Mind your cruise control and acceleration habits, but not in the way you might thinkA close-up of a car's steering wheel with cruise control buttons. - Eugenesergeev/Getty ImagesCruise control seems like an obvious fuel-saver, and on flat highways it is — maintaining a steady speed is more efficient than the small fluctuations of human input. However, on hilly terrain, cruise control works against you.To maintain the set speed uphill, it holds the throttle open longer and harder than a driver would. A driver naturally lets speed drop slightly on a climb and recovers it on the descent. Cruise control doesn't think that way — it just keeps pushing to hit the number, burning more fuel in the process. In other words, most CC systems aren't able to tailor the way they deliver power the same way a driver can.AdvertisementAdvertisementAccelerating as slowly as possible from a stop is another myth people swear by. The logic is sound on the surface — gentle inputs, less fuel burned. However, there's a sweet spot. Crawling away from a light keeps the engine in lower, less efficient gears for longer, working harder per mile covered.The goal isn't to accelerate as slowly or as quickly as possible. Instead, it's to accelerate smoothly and get into the highest appropriate gear as quickly as conditions allow. Most modern engines offer more efficiency at low RPM in a higher gear — crawling in first to "save fuel" works against that entirely.Want more like this? Join the Jalopnik newsletter to get the latest auto news sent straight to your inbox, and add us as a preferred search source on Google.Read the original article on Jalopnik.