Why don't you believe that they have a meeting and discuss their plan before they get to work on a car? Makes sense to me with that many people working on a completely custom project.
Obviously they one they show on TV is scripted, but I'm sure they do something similar once they figure out which car they are going to be working on.
The most fake part for me is when they go to the person's house and tell them they are gonna pimp their car. Oh wow imagine that everybody just happens to always be seconds from the door wearing their best clothes.
The cars are usually ugly and overdone with no useful or attractive features, but every now and then they do something cool. The show is cheesy and not very informative, but compared to the rest of what comes on MTV...well you know.
Overall it's entertaining sometimes, at least it's short.