I cant find any real information on this but it seems like the E37 is capable of flex fuel without the sensor. I have an 07 2.2L HHR that I would like to make flex fuel if its possible to do without adding the sensor. She gets decent mpg now but I know from experience that a proper pump gas E85 tune is a lot easier on the wallet. I see where the 09's got flex fuel and they do not use a sensor and I believe they are both E37's so I assume its just a matter of if the drivers were installed in the 07 PCM.