In the last month and half I have bought 3 HHRS two of the deals went south, the HHR that I currently own Believe it or not. is at the dealer getting work done on it.
I was able to drive the other HHRs for a week each and the had the 2.2
engine auto trans, they both were the LT1 with Auto trans.
on the turnpike doing 61 miles an hour in the slow lane ( pissing even old ladys off LOL) both of the HHRS were getting instant readings of 47MPG-50MPG only when driving on completly flat roads if it went up hill at all the mileage would drop. this was done with the a/c off in the morning cooler temps. on the way home the instant was 32 to 34MPG it is much hotter
around quitting time.
with the 2.4 in my HHR LT2 w auto trans same trip on the turnpike the 2.4
just wouldnt get even close to the same mileage as the 2.2.
unless I went down a back road like jog and was doing 39 mph getting 49-51
MPG.
my new HHR has the 2.4, running boards, mud flaps, and roof rack without the crossover bars. is the mud flaps causing it or a combination of everything
BTW the other two HHRs had a spare this one has the pump.

 

Well the 2.2 is rated at slightly better mileage. Besides, that's extraordinary mileage. Going 60 with the cruise set, at max I can get 33mpg...

 

yeah I am not sure if the mileage is correct it is was shown for instant I know what counts is the range I get out of a tank.

 

it would seem that the cruise control makes a big differance I can try as hard as I can
and not match what the cruise will do. I think that in the morning I may be getting bogus readings. hell my wifes smart car doesnt get 49-51mpg

 

My 2.4 at 62, for some reason is the best speed, on perfectly flat road, no wind, I can get 36-38. But that's really and illusion because there is nowhere to drive that way for long periods. At 45 mph as the torque convertor locks up, I get exactly 46 mpg, but again, who drives that way? Real world, I average 25ish all around I got over 35 on 2 trips and 34 on another.

 

I average just above 30 mpg with my '07 2.4...... use the heck out of cruise control but also accelerate like a bat out of hell quite often....... up to speed limit and then hit cruise. Most of my driving is on 55 mph back roads. Average speed on the DIC when I scroll through and read mileage is usually 35 mph. When I do the math on my gas receipts I find the DIC reads low and my actual mileage average is 31-32 mpg. (stock 2.4 auto, synthetic oil, fresh air filter, lighter weight wheels and tires, 93 octane Sunoco)

The oil, air filter, premium, and wheels all made a difference when I added/changed them. So far everything I've done to the car has made improvements with both performance and mileage, I'm planning a tune (Trifecta tune) and even better tires for next spring.

 

This was me on a straight level road with a car load of passengers and luggage with a strong tail wind helping to push the car down the road. it's a 30 sec clip but was at the end of a 5 minute ride where the avg mpg data was staying at around 48-49)


http://www.youtube.com/watch?v=iLyDdDWU9fU

 

my 2.2 is averaging 25.8 mostly around town, the only freeway trip I was on I averaged 32.5 mpg.

 

It all depends on how I drive it(2006 2.4 auto 17" wheels all stock). I cant really say how I will do on the 93 oct, first tank, but on 87 the absoulte most I have gotten as an average is 40. That was drafting a big rig rather close and sticking it in Neutral as much as I could. But I have also averaged 18.5 on my last long highway trip. Now as I dont have the instant MPG, I can reset the avarage MPG for a more "instant" reading. It only reads 99.9 so I have probly gotten well over 150, thats at very high speed and shifting into Neutural. It helps make up for the quick accerlation that just happened. I usely get between 20-30 though.

 

No your wifes smart car dont unless you got a hybryd version somehow, the best they get going down hill is 36 mpgs,lol many a magizine has tried!