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Has anyone done any quantitative MPG testing between premium and regular?

It seems like the higher octane fuel might combust better, improving MPG...but perhaps not enough to offset the cost.

Has anyone dug into this topic?
 
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Higher octane fuel combusts at a higher temp. Which makes it burn later.

A gallon of premium fuel has the same energy potential as a gallon of 87 octane.

Cars that are tuned to run on premium fuel can inject more fuel and attain more power. They are also properly engineered to provide the proper amount of air to do this.

The CR-Z is engineered to run 87 octane in the USDM.

One of the mpg mileage kings on this board (swat****, I can't remember the numbers in his handle) has been getting excellent economy on premium. But I suspect a lot may be due to his driving technique, more so than the choice of fuel.
 

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Has anyone done any quantitative MPG testing between premium and regular?

It seems like the higher octane fuel might combust better, improving MPG...but perhaps not enough to offset the cost.

Has anyone dug into this topic?
Hey Dereks, I have done a little comparo between premium and reg fuel. Although at the time I started using reg from prem was about the same time the gas stations here in Tx. started to use additives for the winter months. I think I remember about a 2-3 MPG difference. Also figured that by using prem vs reg will cost me 3.00 more per tank. That's about 1 mpg added, for each dollar in added expense per tank fill up, well worth it. You search the MPG forum for all my fuel comparo post, but here is a small highlight: Summer months with premium I was getting 48-51.3 MPG's (full tank averages, never a partial tank) Winter months with prem; 40.547 to 47.8 or 48.7 I forget which. Winter months with reg have been down near the 40-42 mpg range. On another note, I have also noticed the fuel bars go away alot sooner in the winter months. I use to be able to drive to work and back home before I would lose a single bar off the fuel gauge 80 miles round trip. Now I will loose a bar on my way to work, within the first 40 miles. Overall, yes prem to reg fuel does have affects, however, winter fuels have a more dramatic affect compared to summer fuels...
 

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Only reason you might see more mpg on premium is % blend of ethanol on the gas. Most of the gas stations have upto 10% ethanol on regular gas and depending on gas stations, some premium gas has none or lower ethanol mixtures. Due to lower density energy of Ethanol comparing to petroleum it achives slight lower mpg.
But! Since Our Crz was created to save the world from pollution and provide solution to world hunger while having fun, you should use ethanol blended gas.
 

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Hey Dereks, I have done a little comparo between premium and reg fuel. Although at the time I started using reg from prem was about the same time the gas stations here in Tx. started to use additives for the winter months. I think I remember about a 2-3 MPG difference. Also figured that by using prem vs reg will cost me 3.00 more per tank. That's about 1 mpg added, for each dollar in added expense per tank fill up, well worth it.
That's not good math. At 10 gallons, getting an extra 30 miles for $3 means you paid $.10 for each of those extra miles. Even at $3.50 per gallon, if you average better than 35mpg your better deal is regular unleaded. The higher mpg you get, the worse deal that the premium becomes.
 

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That's not good math. At 10 gallons, getting an extra 30 miles for $3 means you paid $.10 for each of those extra miles. Even at $3.50 per gallon, if you average better than 35mpg your better deal is regular unleaded. The higher mpg you get, the worse deal that the premium becomes.
Sorry. Wasn't saying well worth it for just the $3 extra cost, but also the better burn quality of prem will help the engine last longer, burn more efficient, and less gunk build up, just over-all better for the internal engine as well as the exiting results.
 

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Only reason you might see more mpg on premium is % blend of ethanol on the gas. Most of the gas stations have upto 10% ethanol on regular gas and depending on gas stations, some premium gas has none or lower ethanol mixtures. Due to lower density energy of Ethanol comparing to petroleum it achives slight lower mpg.
But! Since Our Crz was created to save the world from pollution and provide solution to world hunger while having fun, you should use ethanol blended gas.
ethanol requires more energy to create than it provides. it is very inefficient, but that's a whole other debate. if what you say is true about the blend, it could actually be worth it to use premium, or possibly mid grade which is merely a blend.
 

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Practically most of the US and Canada use ethanol blended fuel for all fuel grades. There's only a handful of smaller independent gas stations that have non-ethanol fuel. You can find a list of them here.
 

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also the better burn quality of prem will help the engine last longer, burn more efficient, and less gunk build up, just over-all better for the internal engine as well as the exiting results.
That is a false statement.

Use the octane level recommended by the manufacturer of your vehicle. Using a gasoline with a higher rated octane than what is recommended does not give you any added benefits.
 

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^ from a cars.com article.

""Typically the only difference is the additive package they put in the gas," Beard said. The additive package is often put into the gas as the tanker is filled up at the refinery. A common additive is a detergent agent. "The law requires a certain level of detergents in gasoline. Shell, for example, is putting in more detergent. — Whether that has a measurable effect to the driver is debatable."

Detergents have a marked effect on engine deposits. "If you take apart a modern engine that has been running on a modern fuel, and compare this to an old engine that was running on old gas, you can see an obvious difference," Mazor said."

thats the whole point of Shell V Power or Chevron w/ Techron - the premium fuels are at least advertised as having more detergents in them.
 

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That is a false statement.

Use the octane level recommended by the manufacturer of your vehicle. Using a gasoline with a higher rated octane than what is recommended does not give you any added benefits.
Not a false statement. Fuel burning cleaner and easier WILL in fact help the engine run more efficient, cleaner, and YES, will help it last longer. As far as what the manufacturer recomends, it is only the minimum recomendation. I also bet you think using any grade oil has no difference than using a top grade oil. There is in fact benefits from using higher quality products in your vehicle.
 

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I don't get the analogy to motor oil. Premium fuel doesn't mean premium quality. It just refers to the octane rating.
 

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octane requirements are dictated by engine design... compression ratios, ignition timing, etc.

you will not gain any benefits from running a higher octane fuel than the engine was designed to operate on.

however, if you want to insure proper additives are included in the gas you use, consider using a "top tier" gasoline that oil companies/auto manufactures have agreed on as to what constitutes "quality".

I don't get the oil analogy either.
 

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octane requirements are dictated by engine design... compression ratios, ignition timing, etc.

you will not gain any benefits from running a higher octane fuel than the engine was designed to operate on.

however, if you want to insure proper additives are included in the gas you use, consider using a "top tier" gasoline that oil companies/auto manufactures have agreed on as to what constitutes "quality".

I don't get the oil analogy either.
I knew I shouldn't have thrown the oil thing in there. Just trying to show there are diferent levels.
Here's an example of better burn quality. Some engines will deisel or ping on reg. and stop on mid or prem. When fuel burns better, or easier it will in fact benefit your engine. Plus I never said prem fuel is a prem fuel. We all know different stations have different quality of fuels. Prem has a higher octane which will burn better than reg.
I have to go pick up the "Z" from the dealer. I will deffinately inquire about our fuel discussion and let you all know what they say.
 

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I knew I shouldn't have thrown the oil thing in there. Just trying to show there are diferent levels.
Here's an example of better burn quality. Some engines will deisel or ping on reg. and stop on mid or prem. When fuel burns better, or easier it will in fact benefit your engine. Plus I never said prem fuel is a prem fuel. We all know different stations have different quality of fuels. Prem has a higher octane which will burn better than reg.
I have to go pick up the "Z" from the dealer. I will deffinately inquire about our fuel discussion and let you all know what they say.
1. Oil thing disregarded

2. some engines do not like regular this is true. in general, higher compression motors or motors that advance timing like premium. A car that is designed for regular doesnt get the same benefit

3. Premium fuel burns differently - later more specifically. It resists detonation better. All fuel from Teir 2 stations (shell,. chevron etc) have more detergents than required by the EPA. Premium fuel from these stations usually have even more detergents than the regular (which is already more than required). Premium is better than regular in this way also.

i still use regular but im open to trying premium and i recognize that aside from octane there are benefits. maybe im misguided but through all my research and experience with a car that requires premium thats what i've come up with
 

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I knew I shouldn't have thrown the oil thing in there. Just trying to show there are diferent levels.
Here's an example of better burn quality. Some engines will deisel or ping on reg. and stop on mid or prem. When fuel burns better, or easier it will in fact benefit your engine. Plus I never said prem fuel is a prem fuel. We all know different stations have different quality of fuels. Prem has a higher octane which will burn better than reg.
I have to go pick up the "Z" from the dealer. I will deffinately inquire about our fuel discussion and let you all know what they say.
Pinging is also called pre-detonation. The fuel is igniting before it should, hence the term. If the gas ignites too soon during the intake phase of the 4-stroke cycle, it can damage the pistons. Increasing the octane delays when the gas will burn. Basically it needs to get hotter before it can ignite.

Higher octane fuels can help a car that's pinging/knocking, by delaying any chance the fuel will ignite prematurely before the spark.

Premium only burns later at a higher ignition temperature. It doesn't burn any "better". Our cars have anti-knock sensors that adjust the ignition timing if they sense knock. Premium doesnt provide any benefit if the car is tuned for low octane.
 
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