This question makes reference to the air-speed of the kart, thus implying that there are different stats for air speed and ground speed, however I can't seem to find any indication of this in-game.
How do I know the air-speed of my kart?
The chart JohnoBoy posted is close, but uses the wrong units. Super Mario Wiki's page on MK7 has all the values. Here's the short version for airspeed only:
Note that gliders have the strongest influence on airspeed - also note that the gliders with the biggest airspeed penalty have the biggest air handling bonus, so they're not total step-downs.