Premium vs regular gas for maximum ECONOMY

I’m thinking of buying a used 05 Acura RL.

Acura recommends premium gas. I’ve read that regular won’t hurt the engine, but may actually cost more per mile because the engine sensors always try to maximize performance and will draw more gas in order to offset the lower octane.

Is this True? And can such an engine be tuned for lower horsepower and greater economy?

You heard correct, sort of. Most cars that “recommend” premium have engines that were built with premium fuel in mind. But thanks to knock sensors and other electronic wizardry, the same cars can be operated on lower octane fuel. Of course the trade off is that there will be less power and fuel economy will be diminished. The level of diminishment varies wildly, on some cars, like the vehicles equipped with the later incarnations of the Nissan VQ V6 the difference is quite noticeable. On other cars it’s not.

The Acura RL is rated for 18 city/26 highway; it’s hardly a gas guzzler. My take on the matter is that if you are not prepared or willing to pay for the recommended fuel for an upscale/luxury car, then you probably are not prepared or willing to pay for the “more expensive than average” upkeep and repair costs that come with owning an upscale car.

The car is tuned for maximum fuel economy from the factory. And any software tuning you come across will be for increased power, not increased fuel economy.

Since premium is recommended for your car, premium will give you better mpg in the Acura RL. How much better mpg is hard to determine. You’d have to own the car and drive several tankfuls of each fuel and then run the mpg numbers and compare them. Over the test period if the refiners switch from winter to summer fuel it will throw off your numbers so you’d get misleading results.

If you buy the RL plan to use premium fuel. Look for stations that price premium at $.10 more per gallon over regular. Some stations charge $.25 per gallon more. When the price of premium is just too great over regular, use regular until you find premium at a better price. I have 2 cars running regular, and 1 that requires premium so I watch and see huge variations on the price on premium gas in my locales.

On the other side of the coin; if a car is recommended for regular, using premium in such a car will not improve mpg, and perhaps give less mpg than regular.

With the small amount you save with cheap gas, you also end up with diminished efficiency. Engines that are built for high octane gas have higher compression ratios than engines that are build for cheap gas. So although you pay more at the pump for high octane gas, the cost of operation of your vehicle should be about the same as with cheap gas, and your car will run better.