Physics Engine (Kick the tires and light the fires!): Not only has Turn 10 rebuilt the physics engine from scratch, they've also tried to address one of the most glaring problems with Forza 3, the tires. That's why, for enthusiasts anyway, the most important addition to the game is going to be the tire physics. Thanks to a partnership with Pirelli, Turn 10 has completely redone the modeling for tire dynamics. The tire company let them inside their testing system to give the game a soup-to-nuts data download and allow them to directly input it into the game.
That means that when you turn off all the nanny systems, and you're in a car fitted with a set of racing slicks, and you push down the accelerator a touch too hard, you'll slip and slide in the most realistic way I've ever experienced. I found out embarrassingly first-hand in a simulator the perils of such a setup on a ham-fisted and lead-footed auto journalist.
But it's so brilliantly realistic you can't not be excited at the prospect of turning off the nanny systems and letting loose some tire-shredding burnouts on a digital skidpad. Or, in my case, skidding into walls on an all-new track that Forza tried to build to be the best driving road on Earth. Set in the Swiss Alps with three to five different ribbons, it's certainly intimidating. It's also beautiful to look at.
