Premium vs Regular

[DerekS]

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?

[JnC]

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.

[swat49833]

Originally Posted by DerekS

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...

[JnC]

Thx swat for the detailed update!

[wkqkqkfk]

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.

[sirjonsnow]

Originally Posted by swat49833

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.

[swat49833]

Originally Posted by sirjonsnow

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.

[Scotty]

I Googled "Regular Versus Premium Gasoline" lots of reading, I will not be buying Premium.

[lldsandsll]

Originally Posted by wkqkqkfk

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.

[JnC]

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.