In this case, a new game announcement for E3 wasn't leaked! Microsoft revealed Forza Horizon 2 to IGN this morning, though we don't know much more than knowing the game's coming this year on Xbox One and Xbox 360.
As with the original, Forza Horizon 2 is being developed by Playground Games in the UK. The game's Xbox 360 release, however, is being handled by an external studio.
Forza Horizon 2, this time set in Southern Europe, will include an evolution of Forza Motorsport 5's controversial drivatar system, and mark the debut of a weather system.