The LE8 2.2 engine for 2010 puts out 155 HP @ 6100 RPM/150 lb-ft of torque @ 4800 RPM using regular E10 gas. Using E85, it puts out 160 HP @ 6000 RPM/158 lb-ft @ 4600 RPM. Basically, when you run E85, you get a small torque and horsepower boost and the engine peaks at a lower engine speed, which should improve low end power. Can you tell a difference? I am currently running a tank of E85 and I can't really tell a difference besides horrible fuel economy. However, my driving has been mostly around town and on the highway and I haven't punched it much except for speeding up while getting on the highway via an on ramp.

 

Moved into a more appropriate section the GENERAL forum.

 

If what I've seen at the dealership, a 15 - 20% decrease in fuel economy is probably typical with E85. Less "power" in the fuel molecule forcing the engine to burn more. Just a thought.

 

Flex fuel vehicles have 2 fuel tables. The primary is the regular unleaded table. It will default to that table since most only run that. When you run E85 it uses the second fuel table. But everything has to adjust to that table and mileage goes down during that process. Most see that and just run regular in it again making it default back to the first table.

Now if you are willing to just run E85, once all the sensors and adjustments are done, your mileage goes back up. Just remember, you pump in regular again, back to table 1.

regular unleaded, 87 oct
E85 about 110 oct

 

You basically pay by the erg. More power less MPG less $/gallon, cost per mile stays nearly the same.

 

When I had my first 2010 HHR it was with the 2.2
I did use E85 and there was a performance gain, it did feel quicker/responsive.
Yes cheaper price at the pump but uses it quicker than regular gas.
Here's something to read:
E85 vs. Gasoline Comparison Test