What is flex fuel for the. Chrysler Aspen v8 2009

it means you can run E85 (ehtanol) fuel in it or regular gasoline- E85 will lose about 15-20% fuel economy (example 12mpg instead of 15mpg), but often costs less. It must cost more than 40cents less per gallon to come out ahead using E85- if the cost difference is less than 40 cents per gallon, you are better off using regular gasoline.- either way, run your tank mostly empty before you switch between the 2 so your car's computer can correctly identify the fuel- otherwise it can turn on the service engine soon light.