Don't scratch the paint. The track detail is also remarkable. The sunset effect is particularly nice. Nothing takes the stress of the office away like driving recklessly in a very expensive car. Be sure to check the weather forecast before you race too.
Rain effects are fairly good and make the track nice and slick.
Also, the tracks left on the wet roads as your car rips by look all wrong and blocky. These are VERY minor problems, but still worth mentioning. The cars are absolutely beautiful. Makes me want to get out of the video game industry and become a racecar driver. My favorite part about the cars is actually being able to toggle the headlights.