It seems the mileage and HP changed each year the HHR was produced, so my question is what year gets the best mileage and which engine?

 

You are going to get a mixed bag of answers on the mileage. Mileage is really based on your driving technique. I have a 2.4L 2006 HHR auto running 87 octane and have averaged 30.6 mpg for the 81,000 miles that I have on the car. Max HP is obtained around 6200 rpm, now how often do you drive at 6200 rpm? At 70 mph, my HHR runs ~2500 rpm. Unless you are a NASCAR driver and on some track, the HHR isn't running at 6200 rpm.

If you have an SS version 2.0L turbo, it has lots more HP and the 2.2L has a bit less HP than the 2.4L. HP rating can be changed by what parameters where the reading are taken.. 6000 rpm or 6500 rpm.

 

Ditto on the "mixed bag of answers on the mileage"....... Much of what you are seeing with GM's changes from year to year with the mileage is just a "numbers game" they play. HP and TQ numbers is also a game sometimes, but there were a few improvements, I believe the 2.2L got VVT at some point.

Most of us are getting around 30... some lower, it depends on driving technique and what your daily commute is like.

 

I have a 2010 HHR 2.2L (LAP-VVT) and get about 30.9 mpg consecutively, with almost 50/50 driving. I've hit 32.5 once and was absolutely shocked.

I don't stomp on it or anything, I feel like I drive what would be the norm.

 

At first, my mileage was ABYSMAL. I was getting 21-24 MPG. She was BRAND NEW then though. Now, with 6700mi on the clock, shes STILL breaking in a littler bit and I should see somewhat better results. My 2006 Cobalt SS/SC would get 30 consecutively as well.

 

51000 on 09 1LT around 28 on it keep the hammer down to 77 to 83 MPH 2.2

 

My 2011 after 4 months as of today has around the city gotten 24 to 25 mpg combined city highway mostly city . Our only trip aprox 500 miles round trip it got 32.1 mpg not bad wife seems to have a heavy foot ! I get a tiny bit better avg mpg than she does but honestly its not much like 1 mpg more . I mostly run Sunoco and Shell ! Did run a couple tanks of E 85 and boy was that a mistake never again ! avg was about 25% less MPG just awful .

I didn't see a performance lose thou in the E 85 just really bad mpg highway and city

One more thing these little van wagons what ever you call it seem to have a sweet spot on the highway ! Mine is at aprox 69 mph with the cruise control on . gets a tad over 32 mpg

 

Pretty sure Both engines went VVT in 2009.

 

My vintage 2008 2.4 has VVT,

the 2.2 went to VVT in '09 & I believe direct injection, IIRC.

 

2007 2.4L has VVT also.....