It is a fast track. Average speed with an F1 car with a fast lap (theoritical estimate) is 237km/h (
source). Suzuka is 229 (
source), Hungary is 200 (
source) and Monza is 257 (
source). These are all very fast F1 tracks and the 'ring certainly isn't the slowest of the bunch. For reference, Monaco is under 160 (
source). (I calculated those numbers by hand using the lap records times and track lengths shown on wiki pages). You also need to remember that most of those lap records are all made in 2005 with 3 litre engines and the 'ring estimate is for the 2.4-litre f1 car).
The average speed goes hand in hand with the power, on slower tracks you obviously are less hindered by not having much power while on faster tracks the gains from more power are greater. As for why certain car isn't on top of the list and some other isn't, I have no clue
Not saying the 'vette or viper aren't great cars and all that, they just have lots of power* which is essential for a quick lap time around the ring.
*high power/weight/drag-ratio