The best thing about Forza 5 for Xbox One isn't the new physics or anything wanky like that. It's the amount of detail that has gone into each and every car. Compare this Forza 5 vista to a few glamour shots of Chris Harris testing the McLaren 12C GT3 racer and you'll see just how good that game is.
Above is the /DRIVE test from Chris Harris, which shows the car in vivid, beautiful detail.
Below is the Forza 5 vista of the McLaren.
Yes, I know we're comparing two different cars here, but the contours are much the same and they're just as beautiful as each other.
What a brilliant job they did.