i dont claim to know how it works- but this happens for me:
Eco: drives like a beached whale. Steering is unresponsive, throttle is partially controlled by the computer to save fuel
comfort: throttle is more in my control, pushing it isnt as hard, steering is more responsive
sport: throttle is completly in my control, and is really quick, steering is spot on
sport+: weeeeeeeeeeeeeeeeeeeeee