How do I know if mine is or is not flex fuel engine? What's the benefit of using flex fuel?

 

There should be labeling, i believe on the gas cap or inside of the filler door. Certainly your owner's manual will tell you.

The benefit of flex fuel in theory is that it costs less. However many that use it report lower mileage that actually results in higher overall usage costs.

Depending on your beliefs, it could also be a benefit that it reduces dependence on fossil fuels, however the corn used to create ethanol requires fossil fuel to farm, and reduces the food supply.

Lastly, ethanol does not have the shelf life of gas and can go bad, making it a poor choice for any vehicle that goes for a while between fill ups.

 

Ah-hah it looks like I found the section in the manual labelled 'fluids' (duh). It appears all 3.6L motors are E85 flex fuel and I verified the yellow gas cap. I'm surprised flex fuel labels aren't anywhere on the fuel door nor any badge, though. Anyway, hopefully this is helpful for others seeking the answer and I'm gonna try out flex fuel on the next fill up to see if it makes any difference mpg.

 

HAHAh do be alarmed with how bad it is. i laugh (not at you) but car companes try to make it seem so good, but in reality if the e85 is not about 40% cheaper than std gas your loosing money on the milage difference.

 

My 4.7 and anything else I have driven that is flex fuel runs like absolute crap. When I first got my jeep I tried the flex fuel just to see what it ran like and I was shocked at how poorly it ran. I would avoid it if possible

 

It seems to me that flexfuel is more of a gimic to sell, this is not the
reason i got a V6.