This summer I bought a new 2007 Caravan base model with Flexfuel. For the
first tank of gas, I got about 18mpg in town, a little below stated mpg.
Then the mileage kept going down. In cold winter now, it only gets 14mpg. I
exactly followed the advice for break-in, and get services on time. This
never happened to our other new cars. I used to own a '94 Caravan, even
better mileage than this one. I know there are some additives to gas in
winter, but that should not cause so much loss to efficiency.