We use our zafira diesel for the two of us with 2 children. We currently have all the bikes on the roof, leaves lots of space inside for passengers and luggage. We have had 5 people and 5 bikes, 4 on the roof and 1 bike in the boot. That was a bit of a squeeze, so not much room for luggage but ok for a day trip.
Bikes on the roof is good, I also manage to put them on, it’s quite straight forward. The only thing that you need to keep an eye on with bikes on the roof is the total weight limit of the car roof. 4 bikes and carriers will come very close if not over for full sussers. We picked the roof option as we don’t have a Towbar, but maybe a Towbar rack may have a higher weight limit? Also I am not sure if a 4 carrier on the Towbar may be illegal in other European countries? My mum still lives in holland said something about that, unless tat was just certain ones or those heavy Dutch bikes?
The zafira is great though, get one!
Simone