Alvin Z

I bought a Honda Fit Auto Sport on May 2007, the reason i bought this car is because it said 31/37 mpg on sticker, but it only goes around 20mpg,1/2highway/city. i start calling up the dealer ask them what's wrong. they told it's a brand new car, it need times before it breaks in. they tell me to wait. i waited until 1700 miles, it doesn't seem any better, i finally bought it to honda to check what's wrong. they checked the car they told it has nothing wrong with the car. it just because it's summer, air conditions and stereo can cause it getting less MPG. so i test it with everything off. NO AC, NO TEREO, NO WIPERS, NO LIGHTS, samething. i called the manufactory. they told me i should have wait a little more, they told me after the first oil change it would get better. on 3500miles bought it to oil chance and service. i told the guy that my car getting bad milage. they told me i have to leave for more than a week to check. and they not guaranteed they will find problems. HELP