2009 Corolla MPG question

I just got a new '09 Corolla, it's still got less than 100 miles on it, but it seems my average MPG is WAY below the EPA estimates. I'm getting about 21.5 on average so far, which is well below even the estimated street MPG of 27. Does anyone know how worried I should be about this? Is it likely to improve with time, or am I stuck with a bum car? Is there much I can do to improve this?

Well I dont think that you can really get a true mpg on only 100 miles. Thats using less than 1/4 of a tank of gas. Run it on a few tanks and then see what it looks like then. I have an 07 with just a tad over 5000 miles on it. When we bought it it was getting about 25 on the HWY this week we took it out on the HWY again and we got 30 to 33 MPG on 3 tanks. I know thats below what the sticker says but you have to figure that they are driving it in perfect conditions no hills, (I have been told that they test those things at 40 MPH) I am not sure though. My MPG was with the CC on and a head wind and going up and down hills in the northern rockies. Take what I have to say for what its worth. I would not worry about it though. give it time.