So I converter my Cruze to a TRUE flex fuel car today. I installed the 42lbs/hr Bosch "green giant" injector (stock are 24lbs/hr) along with an actual flex fuel sensor and tuned my ECM with EFILive, so I now have an actual flex fuel Cruze!!
Can run what ever fuel or mix I want and the ECM will adjust for it.
This is the write up I used on EFILives forum showing how to do this.
Chev/Holden 1.4L Cruze E85 FlexFuel Conversion
Here is the sensor I installed in the fuel line so the ECM know how much ethanol is in the gas. You can see on my V2 where it's reading 7.8% ethanol right now and commanding an AFR of 14.24. Which is right since I run pump 93oct that contains up to 10%.
Time to put some E85 in it and see what it does. I did this so I can run cheap 85/87 gas and mix in a little E85 (105oct) and get the performance of running 93 but with less cost. I think I can still get close to the same mileage with only about a 25-30% mix.