On the HHR SS You know that you CAN run 87 octane, but are some tradeoffs. Now consider this: Since there are spark knock sensors, that back timing off for lower grades of fuel and other reasons, yes you can use 87 octane. However, EVERY gasoline engine gets optimum efficency at maximum "no-knock" timing, hence the need for knock sensors to fine tune the engine to maximum spark.
IF you get maybe 1 mpg less with 87 octane in the city driving, say from 21 to 20 mpg,(pretty hard to actually measure, but stick with me here) that is a drop of 5%. So you use 5% more fuel, at a cost of 20 cents per gallon ( $4.00 GAS x 5% loss= 20cents). The 20 cents per gallon saved on 87 octane is eaten up, by the extra 20 cents per gallon of additional gas you gotta buy by using it
So it looks like a break even thing to me, except that 92 octane will actually cost the same but gives you much better performance, for no actual extra cost.

 

I don't believe you lose that much miles per gallon. I think there is a misconception that by using 87 octane the engine will constantly ping/knock. Which I don't believe to be true. Consumer reports also says no...but I am sure others will disagree.

http://www.consumerreports.org/cro/c...-406/index.htm

But for what it's worth, if I drove a turbo or super charged vehicle I would burn premium and fuel economy would be my least concern.

Okay all you nay-sayers, chime in.

 

I run nothing but premium for exactly the reasons you said. Get just enough better mpg to offset the cost, so why not use it.

 

I have been running 87 in my SS now for 3000 miles. I really don't notice much of a performance loss at all, and around town I get 23-24 mpg consistantly with 28-29 on the open road.

My biggest savings comes from the fact that as part of my "compensation plan" I get free gas (87 octane) from the company tank. Hard to beat that.

 

Nothing better than zero dollars to the gallon!

 

MPG on my auto drops significantly. I go from 28.5 to 25.9. The loss is equivalent to the spend of using 93.

 

Octane rating = resistance to detonation. The higher the octane, the more energy required to kick off a chemical reaction (activation). This is why higher octane fuels are good for high compression and/or advanced timings. Octane doesn't have anything to do with the gas burn phase (deflagration)

However, I buy "high octane" fuel for another reason altogether... many "premium" suppliers (Mobil, Shell, etc.) create a more beneficial formulation in their higher octane offerings which include more carbon-carbon bonds, which have more energy than other common fuel bonds, such as carbon-hydrogen. In other words, when you're buying their "premium" fuel, you're getting more resistance to knock (higher octane) AND more fuel energy.

 

According to my calculations at todays prices in my area, the price difference between using 87 and 92 is about $100.80 per year.

That is filling up 3 times a month at 14 gallons per fill up.

 

I find using regular in a car designed for premium just to save a few measly dollars to be dumb when you have a $20k+ investment. How cheap can you get? Why didn't you buy the non turbo version of the HHR? I'm one of those naysayers who doesn't believe the pcm can totally avoid any damage to the engine when using an inferior octane, especially when you have to get on your car to pass or enter the freeway. Sure, the damage will take awhile and probably won't be a problem until the second owner, but hey, that's somebody else's problem. I have a friend who has a PT GT (turbo version). He has a scan gauge and put regular in his car to see the numbers. They weren't good so he believes there is damage going on.

 

You quoted my post. But I am not sure if you are directing this post to my quote. I thought I said I would burn premium in a turbo engine and I recommend everyone (except clevelandhhr) do the same. Maybe I am just confused, this has been a long hard day.