Completely ignoring anything having to do with SFB and going entirely on the established science of canon Trek, The SFCIII way of handling movement is fairly accurate. In Star Trek, battles don't usually happen at warp velocities. Here's why.
1. Subspace field -- The subspace field generated around a ship from the warp nacelles is what allows the ship to travel at warp. It changes several physical properties of the matter inside the field to allow this to happen. Otherwise, the ship could only accelerate toward light speed but never reach it. The subspace field does not actually propel the ship. That is done through the impulse engines. The subspace field prevents certain actions from taking place, such as turning because this will deform the ship within the field, launching objects that are not design to leave a subspace field (photon torpedoes and certain probes can be launched at warp), and firing phasers.
2. Impulse engines -- Other than thrusters, impulse engines are the only means to propel a ship ("going to warp" involves placing a subspace field around a ship so the impulse engines can propel the ship at faster than light speeds compared to everything outside the field). Impulse engines CANNOT ACCELERATE A SHIP TO VERY NEAR THE SPEED OF LIGHT. This is not only a myth, it is scientifically impossible (Trek science or otherwise) without causing significant problems for the object being accelerated (relative time nearly stopping, mass reaching near infinity, etc.). There are different classes of impulse engines for different ships that range greatly in power, and a ship's mass has a great impact on how fast it can travel with a certain type of impulse engine.
3. Thrusters -- Thrusters allow a ship to maneuver and propel itself at very slow speeds (compared with impulse speeds). SFCIII only takes into account the maneuvering, but this is fine because forward propulsion by thrusters only would be negligible in the game. It only makes sense that if you equip your ship with better thrusters, it can maneuver better.
Take this information for what it is, canon Trek science which has absolutely nothing to do with SFB. I am not saying that SFC3 is better than SFC1, 2, or OP. In fact, I think that SFC3 has some very serious shortfalls and, overall, OP is the best SFC game ever made.