The answer is categorically NO! the 156 is a lovely car but for four people and their luggage - not really. Look for a Renault Espace. Try and see if they have a Fiat Multipla, or anything which is a van. I know that these are not cheap options, but four people and their luggage is really a lot for any car. If you all take hand luggage - fine, but I expect that this is not really a viable option for you. By the way I endorse all the advice that you have been given.