Picture your car - the one you own right now, the one you first owned, or the one you hope to own someday - racing along the Bernese Alps. It swings along the edge of a cliff face on an impossibly tight corner, and as you look forward you see a drop-off; thousands of feet below and all around you, a valley of snow shines brilliant white. If that sounds like a commercial, it's because that's exactly how I felt watching the Forza 4 demo.
All Forza 4 tracks look to be a dream for those of us who ever watched an advertisement for the latest, greatest model and thought how much fun it would be to own that car, if only we could drive those winding roads and see those larger-than-life sights. The tracks are fictional, as are some of the locations, but their inspiration comes from real-life wonders. The new graphics and lighting engine in particular help bring out a ridiculous level of detail in both the environment and the cars themselves.
Forza 4 will have a Dynamic Competition Model. Class restrictions, opponent upgrades, and a new professional AI setting. In World Tour (Career) the AI dynamically scales, all races are class restricted, and all of the AI are upgraded. You will no longer be able to win races just because your car was so much better than the competition.