This is over ambitious for someone new to Maya, a seasoned pro would find this a challenge.
Car modeling in general will take time for you to master and again is a little above your current skill level, i would start off with something easier like modeling something on your desk so you can learn the tools.
In answer to your question you can model the car in pieces if you have an idea of how you need to animate it or you can model it as a whole and break it apart once its complete.There is no right or wrong way just whatever gets you there.
You have a lot to learn and it will take time and you may never master all you need.
Modelling .Texturing,Rigging and Animation are all fields in their own right and require different skill sets.
Sorry i don't mean to sound negative but you really do need to learn to walk first before you enter a marathon.
2 x Modeling Challenge Winner