Been running 87 since day one. We have a 06 2LT with 29K miles. No issues at all.

 

In my 2.4L, I'm using 87 octane. @$3/gallon 93 octane (91 is NA around here) is $0.20 more than 87 octane.. I'd have to average ~3 mpg more (assuming 30 mpg) just to break even on cost.

I'm averaging 30.4 mpg (according to my 2007 records) with mixed driving. The DIC reads 27.6 mpg now, with around town driving on this last tank of gas (300 miles so far). When I have used the 10% oxygenated blends I have noticed a drop in gas milage of about 10%. Since it isn't any cheaper than 100% gas, it is no bargain for the consumer, but a nice benefit for the corn farmer getting subsidies to grow the corn for ethanol production.

 

I use nothing but 87 octane and have never heard any pinging.

 

Too new to HHR to comment about using higher octane, however, my 06 Impala SS was designed to run on premium with reduced performance using regular. You would hardly notice the performance change, but I got much better MPG out of the premium, making it worth paying the extra $.20 for the premium.Of course, going from 13 MPG to 14 is a major jump in that car. I would have to get a minimum of 1.5 mpg to make it worth while in this HHR