Just did a road trip up the SkyLine(Skyline Drive VA ) and did some offroading in the rain to get to the cabin for the weekend ( really steep incline on a dirt road..oh, did I say dirt? Mud is better)..2 - 75# dogs,,coolers clothes and all that did 31.5 mpg there and with the puttering and stop/starting up skyline. did 28.8mpg on the trip back. PLenty of power for traffic cruising and ..yeah..climbing mud hills! Though I have to credit trac contrl for getting us up there otherwise I'd still be trying! Also found that i got beter mileage at 80 then I did at 65..go figger....36 to 33 DIC must be my "sweet Spot"

 

I noticed a slight increase in MPG. I doubt if it is related to the turbo. There are any number of parameters that may have changed with the new calibration. A VVT DOHC direct-injected motor has a ton of variables.

 

Agreed. I am thinking the tweaking of the trans/ignition control of ports, etc. is what is allowing the better mpg numbers.

 

I just completed a trip from Ventura County, CA to San Diego. We had to leave in the middle of the Friday afternoon L.A. traffic, probably the WORST traffic anyone could imagine. It took us over four hours to get there but today (Saturday)we returned in just 3 hours....mostly flying along with the cruise set at 80 mph. Overall I got 25.0 mpg!!! I think all things considered, that's pretty good for a highly tuned HHR SS with "the kit". Oh sure, I could have done a little better by taking it easy with the on-ramps and changing lanes but what fun is that?

 

The engineer at GM who installed one of these on the first Solstice also saw more MPG.

He feels it is due to more timing and more torque. He feels under normal driving the extra torque gets him up to speed and off the gas faster. Less time in the gas more MPG.

He said this was a unintended side effect of this kit. Note you MPG go up fast coasting as it will stop the fuel all together in the new DI engine. The vehicle does need to be in drive to have this effect.

 

Since this thread got resurrected I thought I'd post my experiences after the stage upgrade. I've got about 2000 miles on it since the kit. My only pure interstate trip was from Atlanta to Montgomery and back at 7 MPH over the posted speed limit and I netted 32.8 on the DIC and over 33 based on actual calculations. My highest MPG pre-stage kit was 31.5'ish. No noticable change in my around town mileage (I actually expected city driving to be worse as I use the go pedal alot more now ).

I reset my DIC average mileage after the install and after 2000 miles it still reads 29.7 mpg but I do considerable interstate/rural cruising miles. 5 speed SS by the way. I used to get 21-22 cumulative in my 2005 GTO to give you an idea of my driving habits/routes.

 

I have over 2.5K with the stage kit now. My city/hwy mpg average is 29.1. I drive 80 miles a day with my commute, so I am very impressed.

Before the kit, only had 1.3K and was seeing an average of 27.1.

 

I have noticed a 3-4 MPG increase since I had my stage kit installed.

 

Yep, I now am averaging 29.5 mpg city/hwy......and it's only getting better!

 

I only had my Stage 1 upgrade installed last Thursday (May 28th), but have logged some limited data that could still be used for comparative analysis:

*Before the Stage 1 installation, with the HHR being moderately loaded for a 200 mile trip including 2 passengers (total of 3 incl driver), we yielded about 27.5 mpg mostly highway.

*After the Stage 1 installation, again with the HHR being moderately loaded but this time for a 300 mile trip with 2 passengers (total of 3 incl driver), we yielded about 30.1 mpg mostly highway (last weekend).

Around town went from 22.8 before the upgrade to 24.5 after with no load and 2 people in the HHR.

Bottom line:

Hwy + 2.6 gain
City + 1.7 gain