HHR - An Aerodynamic Brick?
 

Hi Folks, I had a long drive in flat country this weekend, so I did some gas mileage checks along the way. Man are these HHR's touchy when it comes to highway fuel economy! All checks were made with the windows up, A/C off, and cruise control on. 93 octane. 50 degree temps.

At 60 mph it did a steady 35 mpg. To me, this is fantastic.
At 70 mph it would do 29-30 mpg. About it's EPA highway rating.
At anything over 74, it lost 1 mpg for each additional 1 mph! Ouch.
Also, at highway speeds any nudge of the pedal would cause the instant mpg's to plummet.

If the A/C was turned on, the mileage dropped one to two mpg's at speed.

I am thinking that above 70 mph the aerodynamics are really getting into the picture big-time.

My old Mercury with a V-8 would haul down 26 mpg at just about any highway speed. It didn't seem to vary much at all.

I am seeing that the HHR's mileage responds to a huge degree upon driving style and speed on the highway.

God Bless, Marc

I take mine on a 3 1/2 hour trip monthy and set cruise at 78-79 and average any were from 30 to 32mpg. Ive taken it slower, due to weather, and got almost 40 average. Then again I notice you have the 2lt so the 2.4 mines 2.2 dont know if that has much to do with it but maybe a little

I think those blanked-out side window panels must cheat the wind better..... ;) I am glad you are getting great mileage. My tires are at 35psi, and going harder would no doubt help, but I hate a hard ride. Also I have the GMPP intake. I didn't check the mileage before I added it, so I don't know if it helped. Yes, Elvis is a 2.4 liter.

I rented several Cobalts for Louisiana runs (all 2.2's), and those would get 35 to 37 highway with the air on and three folks in the car. That is what led me to buy an HHR, it's the Cobalt "wagon".

God Bless, Marc

Hey Marc,

I Have Yet to Try and See What My Mileage Actually Is! Not to sure if the Display of 17.6 Miles per Gallon is Correct But if so I'm Glad We Did the 140 Speedo Install :lol:!

Since I have installed the GMPP intake I have considered it unfair to check my in-town mileage.......vroooooom. :D God Bless, Marc

Ok, my stock 2.4L (w/Mobil full syn) in town is getting a steady 26mpg on 93 octane. And on the super-slab, cruise set to 75mph, shows 31 mpg.

Our windshields are laid back pretty good to cut wind, imo.

Imagine what an old box van would get ??

depending on how I drive I get high 20s in town my max achieved in town is 32mpg. I couldnt really believe it till I caculated it out and sure enough 32 and only done that once normally right at around 28-29mpg.

You're doing better than I am. I guess I better get an egg under my right foot. ;-) God Bless, Marc

Yeah I checked out ecomodders.com and they have a lot of advice and techniques mostly geared to a manuel, wish I had one. Any ways they have a lot of mods to improve mileage as wheel most I will never do as it looks tacky some times but will be trying a few I think.

That's absolutely incredible. Seriously. You probably got lucky with an ultra-perfect tuned engine. Have you written GM any letters about this? I'm sure they would pounce on something like this for their promos.