The top gear website is doing a competition to win a seat in a Santander two seater grand prix car at silverstone during the Grand Prix driven by the stig and all you have to do is register for the newsletter, theres some pretty good runner up prozes as well, for more details heres the website
http://www.topgear.com/content/news/stories/2932/
http://www.topgear.com/content/news/stories/2932/