We purchased our Scion new and have about 62k miles on it now.
I forget exactly the numbers, but the mileage during the first 5k miles or so was noticeably lower, by maybe 10 percent. The first 1000 miles was the lowest mileage we've ever recorded.
Here are the annual reports for a broad overview.
http://www.fuelly.com/driver/bdc/tc/annual
But I've heard it said more than once that the EPA average for these Hyundais (as well as many new American cars) is a little optimistic.