ramblemutt-

Yes timing chain in all hhrs.. Suggest you test a few & see how you like them..

As far as altitude, the ECM will compensate for that.

& the hhr line up is as follows:
1) LS = base model
2) 1LT = next step up, could have been ordered with either 2.2 or 2.4 ...
3) 2LT = most loaded HHR, 2.4 (only) & depending how it was ordered, could have all the bells & whistles.
4) SS = Hot Rod with the 2.0 & turbo.


Having a sunvisor will hurt mileage, my 2.4 is averaging 32+ mpg @ 70 mph.

 

Thanks for the info Sleeper

 

I'll be out testing for the next couple of weeks....will update.

 

Good luck. if you have any issues or question just post up what it is.

 

Ur welcome HHR SS 818........

 

My 06 2.4L HHR has a bit over 100,000 miles on the clock. I have used mosly 87 (regular) gas in the car. I have done some "experimenting" using premium (93 octane) and saw no increase in mpg. ( seat of the pants I felt that there was some better performance gains) The $0.20-0.30 cents per gallon higher price for premium, I couldn't see that price differential any benefit, but just making my wallet lighter. In the six years of ownership, my overall mpg is a tad over 30 mpg. I haven't done much driving the HHR in a mountain environment. This summer while on a road trip in Colorado, (in another car) I noticed that regular gas was 85 octane and that car did not suffer with lower mpg using the 85 octane at the high elevations.

 

My 2.4 gets 34hwy and about 27 around town. I always run 87 no issues.

It's all in how you drive it. Good luck

 

My 08 has a 2.2 in it with 178656.0 on the clock. Still gets 33hwy and 27 in town on 87 no problems.