I HATE permutations and all of the sort... Just despise them... HATE probabilities too... However, I'm gonna give this one a shot just because I need to teach my brain not to go catatonic on me when it comes to these types of problems.
Here's how I see the damn thing:
First of all, you have three ways of setting up the front seats: parents, parent +girl, parent + boy.
If both parents are on the front seats, then you have two ways of arranging the back: girls either on the right or on the left. Since each parent can be the driver, you get 4 ways of arranging this freakish Adams family.
If you have a parent + girl in the front seats, then in the back you can arrange them in 3! = 6 ways. Again, since you have two parents and two girls, you get 3! * 2*2 =24 ways of arranging them.
Last but not least: if you get parent + boy, in the back they can only be arranged with both girls on the side and the other parent in the middle, which gives you 2 possible arrangements (girl A on right, girl B on left versus girl A on left and girl B on right). Since there are two parents, you get another 4 ways of setting them up.
That makes a total of 4 + 24 + 4 = 32 damn ways of having them set up...Sorry for my rant... Hope you understand smth of this rumbling...