I think we have a cultural gap here of some sort. Here in the states when contemplating the question of what vehicle with which to tow a car-loaded trailer, we would not be thinking of a Volvo - we would be thinking of a humongous truck. The essential problem is that rear wheel drive is better for towing but most RWD Volvos are 4 cylinders with like 114 HP. The best Volvo for the job would be one you built yourself - a RWD customized with a huge V8 engine - which is not as far fetched as it might sound - there are people in the US who do such conversions. But seriously I would be very surprised if a Volvo was the right answer for your task.