We don't live in Dublin, but in Cork, and we have just the one car. No kids at the moment, but will be in the future. Living in the city, so the car is just really for going away the weekends, big weekly shoppings and the likes. The real problem will come if we move out of the city (which we are planning to do soon), because while I work 9-5.30, my partner does kind of shift work, and the area we want to move doesn't have good public transport services...meaning we will both have to drive either to the nearest train station (their service hours are the worse i've ever seen), or drive into town, looking for a parking spaces, etc etc. We will end up having to have 2 cars.
Regarding SUV, it seems to be the trend right now, not only in Ireland, I have been in Madrid recently (my home town), and it looks like all the new mums are all getting one....nothing against them if they are going to feel safer.
I reckon I would consider giving up my car if the adequate means of transport were in place...