The selection of a car is something the requires a lot of expertise. What this means is that oyu should get a car that is worth the money that you are paying. The rule of thumb is that oyu should not pay a car that is not worth the investment.
If you are to buy a brand new car only to take it apart and put some new stuff in it, you are actually better off with buying a junk one and making it into something new. There are some great bargain deals that you can get at a nearby second hand car store. These deals are all dependent on how the car has been used and what they actually look like. You may think that this act is not worth it but if oyu think hard about it, there some car dealers who do not care about the model or brand of the car if they are old.
Only the collectors and the hardcore car fans are the ones who are into this type of thing. spending a little on a vintage and rare model is more admirable then spending so much on brand new and have almost zero upgradability.