Family goes on vacation in their RV. RV is hijacked with the family in it.
Just a long shot, have never seen it, but maybe PRESSURE POINT (2001)???:
Wow! This may well be it! Just viewed the trailer and it has many of the elements I do remember (and many I don't, so much of it will be new to me) and the age of the film is about right. I will watch this tonight! I must tell you that I have been looking for this movie for the last 10 years off and on and have tried just about every "find that movie" site out there, receiving dozens of suggestions and yours is the first that comes close to the mark! Much thanks!