I think the missions in RayCity are way ahead of it time for any MMO, let alone an MMO Driving game. The city is littled with NPCs, of course, this happens in almost every MMO however the way these NPCs react to the driver is amazing.
After accepting a missions, you have ways of improving your performances so the passenger or quest give can give you a better rewards. You can controls your vehicles in different ways depending in which missions where given to you.
The 'taxi missions' usually have the NPC enter the players vehicle as they accept the missions. Other missions include a chase mode and delivery missions.
The Chase Mode allows a vehicle to accept and the player can strafe to ram into the other vehicle during the missions.
The delivery missions has the NPC throw an item in the boot and you driving around to checkpoints. Towards the end, the item gets 'thrown out'. As humour as it looks, no other Driving MMOs (not even Need for Speed World) has been able to present such a feature.