How can a path animation be used as an action in the game engine? I animated a rollercoaster using a Bezier Curve and a Follow Path Constraint affecting the vehicle. 
Then I tried to use the automatically created action in the game engine but the Action Actuator has no effect . 


How can this action be used in the BGE?
Can the Path Animation alternatively be converted into keyframes?
You can convert actions such as constraints to keyframes with Object > Animation > Bake action. (see this)



You may want to enable Clear parents to replace parent/child with keyframes:



Also note that without Clear Constraints enabled, constraints will not be removed, possibly giving unexpected results.