To celebrate Gran Turismo's 15th anniversary, Polyphony Digital and Sony are teaming for an announcement of some sort on May 15th.

The event will be held at Silverstone Circuit in the U.K. next week, and though both Sony and Polyphony are touting it as a celebration, all signs are pointing to some kind of announcement coming. If that teaser image of a mystery car underneath a tarp wasn't enough, there's also the numerous rumors that have been circulating about Gran Turismo 6's supposed release.

“The Gran Turismo franchise continues to be extremely important to PlayStation,” explained Jim Ryan, president of Sony Computer Entertainment Europe. “We felt that 15 years of GT was an event worth celebrating along with our colleagues from the Americas, Asia and Japan. We are very grateful to our manufacturer partners for helping us to bring together a fantastic event. As well as experiencing the development of the game and comparing the virtual and real, it will be a pleasure to see Yamauchi-san and hear what’s next for Gran Turismo.”

The real question though isn't what, but more of a when. With a new console coming out (even though GT6 was rumored for PlayStation 3), it's entirely possible Sony could be lining up Gran Turismo 6 for the PlayStation 4. We only have a week until we find out, but it will certainly be interesting to see Polyphony's big surprise.