Does putting in the more expensive gas give you better gas mileage?

Question

And if it doesn't.......then why do they sell it? Does it just give you a cleaner engine so it will last longer?

Answer 1

With modern cars, the owners manual will specify the octane to use for optimum gas mileage and performance.  Using more than the factory rating is just wasting money.  A car with a recommended octane rating of 87 isn't going to benefit from using mid grade or premium.  However, a car that specifies premium needs premium; using anything less could cause the knock sensor to throw a check engine light, poor drivability, and detonation (really bad, can cause engine failure).

Unless your motor is modified in a way that it requires premium (advanced timing, installation of higher compression heads, agressive cam profile, etc), and the manual says to use regular octane, don't waste your money on the expensive stuff, especially with the way gas prices are.

Answer 2

No

Using high-octane gas in a car designed for regular accomplishes little except more rapid combustion of your money.

High-performance cars often require premium gas because their engines are designed for higher compression (higher compression = more power)

Some refuse to believe this, claiming, for example, that premium gives the family Toyota better mileage or more power. These people are in dreamland. Others say premium is purer or contains detergents that will cleanse your engine of uncouth deposits. Likewise misguided thinking--government regulations require detergents in all grades of gasoline. (BP Amoco, I notice, asserts that its premium gasoline contains more detergents than legally required; if you think that's worth 20 extra cents a gallon, be my guest.) Some automotive types claim that using premium in a car designed for regular will make the engine dirtier--something about deposits on the back side of the intake valves. I've also heard that slower-burning high-octane gas produces less power when used in ordinary cars. Believe what you like; the point is, don't assume "premium" means "better."

Cecil Adams can deliver the Straight Dope on any topic. Write Cecil at [e-mail].

Answer 3

ok, here's the deal.....if you are just driving out and about town,  use the least expensive 87 octane you can find in your travel.  IF you are taking an extended trip , say 100 miles plus, where you will be doing some set speed cruising, go for the 89 octane stuff.  my experience with my 4.3 V6 envoy, gets almost 1.5 more miles per gallon than with the 87 octane.  that's my experience, and may not be yours, but give it a try.

Answer 4

No, the more expensive gas just has higher octane content.  This is in order to prevent engine knocking.  If your engine is designed for the higher grade and you put in the lower grade, it will cause problems.  Fuel efficiency has nothing to do with it.

Answer 5

No.

Maybe if you have some fancy Ferrari that NEEDS high octane gas to work right but that's it.