I wouldn't have minded the car placement but it was unrealistic to the story and the family. Of course the father wants to give JJ anything and everything he can, but this is the family that couldn't afford to send him to college just a year earlier. Now they are buying a brand new car?
And, I gotta ask, why is suddenly ok with the adults that Roxanne is living with her boyfriend? Who is paying her Catholic school tuition? Believe me, without it she'd be outta there, and if they knew where she was living she'd be expelled. Her mother apparently doesn't care, but the Pryors aren't likely to lie for her, nor to keep quiet about the situation. Even with Beth and the baby to soften them, Roxanne is still a high school teenager, not even as "adult" as JJ and Beth were.
The kids are not going to get away with lying about that fire either. Or maybe I'm getting mixed up by modern day CSI's.