I have always been confused as to why sport compact mags feature cars such as the 240/Silvia, Skyline, RX7, NSX, Supra, and 300z. These are true sports cars. I think the US has a horrible tendency to label anything out of Japan as a "sport compact", either that or "Sport Compact Magazine" needs to think about a new name.
In a traditional sense, a sport compact car is just that...a compact car. While some of the cars named above may be classified as a sub compact due to small interior volume, the actual size of the car is pretty large. I was just sitting next to a Scion in traffic today marvelling at how much of a boat my car seemed sitting next to that little car.