Premium Gas

[kdk84]

Hi I just bought a Prius last weekend. I have read a lot of topics that people have found decent changes in MPG by visiting different gas stations, presuming that there may be some difference in gas quality. I was wondering if anyone has ever tried putting a few tanks of premium through the car and if they noticed any better gas mileage due to the higher quality gas. I was just curious as to if anyone has experimented with this, thanks.

[seasalsa]

I have done it a few times when the station was out of regular. No noticeable change in MPG.

[darelldd]

<div class='quotetop'>QUOTE(kdk84 @ Apr 28 2007, 07:51 PM) [snapback]431941[/snapback]</div>

I was wondering if anyone has ever tried putting a few tanks of premium through the car and if they noticed any better gas mileage due to the higher quality gas.[/b]

1. "Premium" is not higher quality gas.
2. "Premium" has less caloric content, and all things being equal, will give you lower (insignificantly, probably) gas mileage.
3. It is currently illegal for a gas station to sell premium as being "higher quality" or better for your car (at least in CA - not sure if this is federal - Unocal 76 paid out quite a bit of money in a settlement a few years back).
4. It takes more energy (and creates more pollution) to make "premium" gasoline. Because of this, using Premium pollutes more than using regular.
5. A car like the Prius (and at least 90% of the cars on the road) get no advantage from using "Premium."
6. The only thing Premium is used for is to prevent pre-ignition in high-compression IC engines. You pay more money for your gas to burn slower. The gas doesn't make any car go faster, or get better mileage - it simply allows a high compression engine to operate most efficiently. If a given car doesn not require hi-octane gas, don't use it.

Did I miss anything?

Oh yeah... no, nobody will notice gas mileage improvement by using "Premium" in the Prius. (In case that wasn't obvious.)

[kdk84]

haha thanks for clearing that up!

although it seems like "allows a high compression engine to operate most efficiently" would mean that car would get better mileage.

But as you can tell I know nothing about cars or gas for that matter!

[F8L]

<div class='quotetop'>QUOTE(kdk84 @ Apr 28 2007, 11:31 PM) [snapback]432029[/snapback]</div>

although it seems like "allows a high compression engine to operate most efficiently" would mean that car would get better mileage.

[/b]

Only if the car is tuned to require the higher octane to keep it from detonating (pinging) due to agressive timing or high compression or both. Otherwise it is a waste to run higher octane than required by your specific engine and tuning profile.