Don't think of it as a hidden stat, but rather a difference in overall handling through out the various situations you encounter. The ship stats are a good clue to follow to discover a ship's hidden potential.

I never got around to finishing my analysis of each ship, but I can provide another example. If you read any of the background about the teams, you'll find that Icaras and Piranha each boast that they have the fastest ship. On paper, each has a maximum speed at 100%. What they don't tell you is that the Piranha will get slightly more distance from a turbo (meaning if you use a turbo on a straight, it will last a split second longer). That being said, when you use a turbo on a straight in an Icaras, there is slightly less of a delay from when the turbo is used than with the Piranha (meaning that the Icaras will boost slightly quicker at the start).

Likewise, the same can be said for just standard acceleration to a maximum speed. Icaras will get to the max speed faster, but the Piranha will stay there slightly longer if you were to let off the acceleration.

Now with the Hairmau, it gets the benefit of handling very responsibly, but has enough weight to it to be able to maintain lines. Compared to the Assegai, the Harimau handles on paper about the same. However, once the Assegai is in mid-air, it is much harder to control and it feels a little loose. The Harimau's weight and back weighted chassis makes it slightly less easy to initially turn, but holds a line much better.

This makes Harimau an ideal choice on Phantom because even though the Assegai handles more responsively initially, it is much easier to go off your racing line. FEISAR is unique in that many people refer to it as a "sticky" ship (meaning it has excellent initial responsiveness to handling, but will pop back on to your racing line much easier than both the Assegai and the Harimau). Of course the downside to the FEISAR has always been top speed. Once again though, in Phantom, it is not as big of a deal. The FEISAR also handles well enough that you don't have to brake as much and a lot of chicanes can be handled without braking or sideshifting where the Assegai and Harimau will need a slight tap on the airbrake.