HHR SS Topics and information on the 2008-2010 Chevy HHR SS Turbocharged models.

What's your highway gas mileage ?

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Old 04-16-2019, 07:17 AM
  #11  
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Originally Posted by Cat Man HHR
OK there are two differences I see.
You don't do short runs and the GM tune upgrade was a plus.
If I turn on my Trifecta tune mileage doesn't increase.
I know the ECM learns your driving habits. In your case your mostly "highway" and it has taken that into account for possible better mpg ?
George do you reset your mpg on the DIC everytime you fill up ?
Yes. I reset all the averages (mpg, trip, avg speed) at every fill up.
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Old 04-16-2019, 08:01 AM
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Originally Posted by Ohiocruiser
18mpg is a horrible number. I average 27-30 with 90-10% hwy city driving. 2010 ss with 125k miles.
That's two that get better mileage than me.
Car runs great. There's got to be a reason.
Always use premium, tires are inflated correctly, drives straight and no performance issues.
The only thing I have to check is the air filter now that weather is warming up. But I can't see a filter being that dirty to have a vast mpg difference. I mean if it was that bad the car woundn't run as good as it does.
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Old 04-16-2019, 08:08 AM
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Originally Posted by Ohiocruiser
18mpg is a horrible number. I average 27-30 with 90-10% hwy city driving. 2010 ss with 125k miles.
Agree. That is a big disparity. Do you have anytype of aftermarket tune? What is different about your's?
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Old 04-16-2019, 08:37 AM
  #14  
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Originally Posted by Cat Man HHR
That's two that get better mileage than me.
Car runs great. There's got to be a reason.
Always use premium, tires are inflated correctly, drives straight and no performance issues.
The only thing I have to check is the air filter now that weather is warming up. But I can't see a filter being that dirty to have a vast mpg difference. I mean if it was that bad the car woundn't run as good as it does.
I highly doubt dirty air filter can cause such a dramatic drop. I woud check the tune with reputable tuner.
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Old 04-16-2019, 09:18 AM
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Air filter has nothing to do with it even if is blocked. This isn't a carbureted car.
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Old 04-16-2019, 09:42 AM
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? So, the dirty air filter doesn’t block the air flow and and increase fuel consumption?


Cat Man , what air filter set up do you have on your HHR? Paper or oiled?
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Old 04-16-2019, 01:05 PM
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Not in the same sense of say a carbureted engine. Crude explanation, Mass Air Flow Sensor measures amount of air coming in (grams/sec) and fueling is then determined by that and what the wideband O2 sensor is reporting on an SS.

There are a number of cross checks based on throttle position, rpm, map sensor that will compare what it should be seeing for air flow and if air filter is blocked/air flow is low it will throw a code long and go into limp mode before it effects anything drastically.
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Old 04-16-2019, 02:55 PM
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OK mystery solved.
Cleared the MPG and average MPH on the DIC. Reset the trip odometer also.
Took a ride to a friend's house 22.5 miles away.
On the expressway the traffic was good for a little bit and then bottleneck stop and go. Got onto another highway and traffic was good.
I got 19.1 mpg and average speed was 15 mph.
On the return trip traffic was better and I got 26.7 mpg and average speed was 43 mph. Again I hit some stop and go but not like in the morning.
Both times cleared info on the DIC.
I never clear this info and thought the mpg that I originally showed (18.1) would have changed as I drove highways, I guess not. If it did it was in small increments.
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Old 04-16-2019, 03:35 PM
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That explains it.
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Old 04-16-2019, 08:08 PM
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I drive mostly highway and I see anywhere from 26-28 mpg. The car has about 190k on it with ZZP stage 1 tune, 3 bar maps, ZZP intake and ZZP catted DP.
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