NPC entering and exiting a car with animations

Hello,

I would like to implement a system where an NPC can enter a car, be driven somewhere, and then exit it. I think I can code that, but what I'm having difficulty is handling the animations. Most of the posts I read through here have solutions where the NPC/player is instantly teleported into the vehicle, or they're made invisible. I want to be able to have the NPC being able to open the vehicle door, get in and sit, and then exit through the same door, and move the NPC position so that they're in the car. How would I do this through Mecanim?

One thing to note is that I am using Unity's NavMeshAgent; currently my NPC only has a walking animation (still need to add in an idle animation). What problems am I likely to encounter to get something like this to work?

Thanks!