The body may not have been buried at all, but put under the grass and leaves. It looks like an old hay field. In some of the articles they call it a "waste place" - lots of weeds, etc. They may have to dig now because it has been so many years.
I was on this case day after day when it first began, and the parents did indeed have plenty of time to move the body, especially considering this field is within walking distance, and certainly easy driving distance. No one was following them around at first. They were going out running every day, and no one was with them at night.
Madeleine's DNA was found on a windowsill and cadaver dogs later hit where a couch under the window used to be. One theory was that the child had an accident and fell while the parents were out that night and they covered it up. Also they had a rental car in which they took several trips while the investigation was going on. There was an odor in the car and I think dogs hit on that as well, but Gerry explained it away as the smell of chicken bones from garbage they took to the dump.
This article says DNA was found in the rental car too.
http://www.telegraph.co.uk/news/worldnews/1562710/Madeleine-McCann-DNA-an-accurate-match.html