The old Galaxy (VW Sharan/Alhambra) used a VW autobox which can be fragile when worked hard - Galaxy plus caravan is a lot of weight.
The new Galaxy (S-Max/Mondeo) uses an Aisin-Warner autobox made by a division of Toyota and fitted to Lexus, Toyota, Volvo, Opel, Vauxhall. It's capable of handling high torque like the 3.0V6 turbodiesel Vauxhall and has an excellent reputation.
Modern autoboxes have zero power loss at cruising speeds by using lockup clutches to eliminate the torque converter - there is still a power loss during acceleration but the torque converter more than makes up for that.