Im unclear on the advantage of performing this talent as a maneuver instead of an action .What is the point of talents like this if you can only perform one action a round anyways? Thanks!

1) It lowers the difficulty to increase the top speed.

2) Increased top speed can be beneficial for chases and the gain the advantage action - performing the full throttle as a manoeuvre means you can gain the benefit of it and then perform a gain the advantage action in the same round (optionally you could also suffer strain and the ship system strain and you can accelerate to the new top speed before gaining the advantage too). The increased top speed also allow you to cross more range bands in one round. Particularly effective if you also got Supreme full throttle.

just remember that if your ships normal speed was 3 (or lower) to begin with, full throttle will NOT let you use 'gain the advantage'.

pg. 136 the ship cannot perform actions of maneuvers it could not perform normally (minimum speed requirements)