Don't worry, hardcore racing fans. Forza Motorsport 4 isn't just a racing game for the Kinect. In fact, it's a regular Forza game with all the gearhead details you've come to know and love from the series... just with some little added Kinect bonuses.
In the showroom, you can lean or step to the side to virtually move around the car, and use your hand to activate action icons that open doors, hoods, and whatnot. They can also activate little informational segments with voiceover revealing information about the vehicle. It's a very cool effect and with the tremendously realistic graphics the Forza series is known for, makes exploring the car seem even more dynamic. You could do the same thing with the controller, but it wouldn't be nearly half as much fun.
Oh, and you can also climb into the car to sit down where you can honk the horn or even start the engine to enter a race! However, when racing with the Kinect, you don't actually apply gas or brake. The game will take care of that for you all you have to do is steer. That proved more difficult to do than I'd expected, and I even chose to sit down instead of stand. You just hold your hands at 10 and 2 and turn an imaginary wheel, although I was told you could also use anything from a plastic steering wheel game accessory to a Frisbee since it just tracks your hands. And while the demo race was rather long, apparently in the final game, they'll be much shorter so you don't have to worry about your arms getting tired.
If it was a Kinect racing game, I'm not sure I'd be into it because it honestly doesn't control all that well. Maybe you'd get used to it over time, but who knows? However, as a kind of bonus add-on to the regular Forza 4 experience? It's kind of cool.