Good grief! Our 2007 2.4l auto trans HHR just isn't cutting it. The average mpg's we're seeing is near 22 mpg! So... I took the advice out here and took the car back to the stealer to have them check if the PCM had the latest program. It didn't... so they re-flashed the PCM with the latest code. That was about 2 weeks ago.

So... this weekend we took the car out on the road for a test. Drove about 160 miles down to see the extended family. I drove this thing like an old man, and it got just over 22 mpg. I used the cruise control and ran the speed limit - mostly 70 mph, but some 55 mph. I was terribly careful to not accelerate hard anywhere at any time... and I coasted as much as I possibly could.

I had high hopes when we pulled into the gas station - DIC was reporting average econ of 31.6 mpg. However... hand calc showed the miserable results - 22.3 mpg.

This is ridiculous!!! My 7000 lb 4x4 Chevy Silverado w/Duramax diesel gets better mileage than this... at the same speed!

This car has 36k miles on it, and I'm ready to get rid of it. Does anyone have any thoughts on what the Sam Hill is going on??!?

 

Something is wrong with the car or driver. My '06 HHR auto w 2.4L has been getting over 30 mpg of mixed driving (30.3 mpg) since I bought it. The worst I have gotten was around 25 mpg of mostly around town driving and I do drive like a little old man. 27000+ miles on the odometer and I do a lot of coasting and cruise control on the highway.

Are you dragging the brakes or are the brakes dragging?

 

I don't have the best of mileage either, but nothing like you are reporting. My last road trip I averaged just under 25 MPG. But I was driving at around 80 MPH and rarely if ever drive like a little old lady.

With mixed "in town" very short trips and 12 mile trips into town, I am averaging just under 22 MPG. Not great, but still better than my old car.

I may have to look into the PCM programing. I guess that it couldn't hurt.

Also, I find it difficult to believe that the DIC was that far off. I know that they can be innacurate, but almost 10 MPG off? WOW

 

I can tell you that there's nothing wrong with the driver. I thought there was when my wife was driving... but she can drive like a 90 year old or a 17 year old and the mileage doesn't vary much at all. I drove more than 320 miles this weekend, and I drove this thing like there was an egg under the accelerator. I checked mileage down in Bowling Green (had some town mileage on it too), and then filled up, went straight to the highway, then filled up just before we got home... 99.8% highway mileage. 22.3 mpg!

I'm gonna give the stealer one more chance to straighten this thing out... and I'll have 'em check the brakes - both standard brakes and the e-brake. Any other ideas on what might be the cause of this? I checked the air filter, and it looks virtually new. At 36k+ miles, are the plugs likely needing changed? This was a GM program car, and it's a certified used car, so I still have b-to-b warranty until 39k miles and 39 months.

We traded a full size conversion van for this car, hoping to double (or more) our gas economy. As it is, we improved it 3-4 mpg - that's it. If I can't get this to improve, I'm gonna trade it for a Prius - I can easily double this current crappy mileage, and save at least 70 bucks or more per month over our current operating expenses.

 

How cold is it outside? Mine gets around 30 avg when its warm but once it starts going below 40 my mileage drops. It`s been cold,days in the teens sometimes,and I`m getting around 25.5. Also whats the hill situation in your area? We`re flat up here.

 

Air pressure in tires?

 

Temp was between 45 and 60 degrees. Warm snap in the middle of the winter. Air pressure is 32 psi.

Terrain between here and Bowling Green is mixed - some hills initially, then flattens out. Oh... BTW... coming home today, most of the trip had a killer tailwind.

One other thing. This car is 100% stock, with the exception of ventshades and a bug deflector... and we only burn regular unleaded.

 

I'd certainly be concerned, too. My '07 2.2L has 3700 miles on it, and drove it down to our little get-away place in Alabama this weekend. 210 miles down, 210 miles back. Filled up as I left home Friday afternoon and got on the interstate. Arrived home tonight with under a quarter tank left. DIC says average speed of 63 MPH for the trip, and 31.6 MPG. Guessing that I have less than 2 gallons left in the tank (conservative guess) means that I used approximately 14 gallons. Puts my MPGs at 30. My on-board computer in my '03 Impala was between 1.8 and 2 MPG off (high). So it looks like the DIC in my HHR is in about the same range. This is my second trip down to AL in my HHR, and my gas mileage on both trips falls into the same range. I cruise 70-75 on the interstate (the majority of the trip) with the cruise control on.

 

Drove home last night at 70 mph on cruise and got 25.8 in 45 degree weather - about 160 miles. Reset everything and watched it start out at 31 mpg and go down from there, finally settling in at the 25.8.

I have an '07 2.4 with 1800 miles on it. Someone on the forum suggested that moving up to a premium gas might improve it. Am not totally dissatisfied with the mileage, but if you can believe it, when I first got my 2001 Aurora with the 4.0 Northstar, I got 29 on the highway. It now gets more like 22-24 with 93,000 miles on it.

By the way, has anyone noticed that when you go from low-beams to hi-beams, there is an instant of no lights at all - like a 1/10 of a second, but it is noticable....

 

DIC was off by a mile tonight - the stupid thing reported 31.6 mpg... not even close - nearly 42% optimistic! My truck experiences similar odd DIC behavior, but that's because I have a tuner in it. Imagine seeing nearly 36 mpg in a 7k lb truck - you know something is not adding up.