sorry to hear ya dont like yer car. with the price of gas being the way it is, you should be able to get a good price for it. but seriously, its been said here. wind generally blows in the same direction. so if the wind speed was even 10 mph which is pretty normal. that can cause a huge increase in gas mileage going one way which in turn can cause a big drop going the other. driving into a 10 mph wind at 60 mph is the same as driving in no wind at 70 mph. in my Prius, i go from 55-58 mpg to 48-50 mpg in the summer. so as you can see. going one way can be the same as driving 50 mph and so on.
too bad some of us are so obsessive- wondering what the complaint may have been when the old vehicle got 18 mpg instead of 20???????? Just drive it and have fun!!!!