Now that I have completed my journeys, I would give people what really happened with my chauffeur-drive bookings.

Dubai - Almost all their cars are Volvo station wagons so our party of 3 ended up all in 1 car comfortably with enough baggage spaces for all our baggage (just tho). They do have Viano but they seem to be used for larger groups and mostly ones to the long connection hotel (i.e. Le Meridien) where they gathered a small group and then dispatched all pax together. I called Emirates in Dubai and they confirmed that the Viano's are limited in availability so cannot be guaranteed - if concerned just get more than 1 car.

Venice - A mini-van (7-seater) was provided

Sydney - A Viano (7-seater) was provided.

In all places, we never received a phone call from the car companies. Not sure if this is because they have to call an overseas number as I am roaming, but even for Sydney I didn't get a call either. However, they all arrived on time and drivers courteous (the ones in Dubai seemed more...not sure if that's because they are expecting a tip).