Shade -
There is a maximum towing weight quoted for most if not all vehicles just like the US. Anything being towed is limited to 60 mph by law anyway - like all of our limits this is from the days when cars had 1.2 litre OHV engines, live axles, leaf springs and drum brakes. The problem is not really the vehicles these days but the roads and drivers.
Roads - For quite a few holiday areas in the UK - Devon and Cornwall or the North of Scotland or the pretty bits of England and Wales the motorway network does not go. In Scotland for example it runs out about 1/3rd of the way between the border and the northern coast - about another 2-300 miles. It is two lane roads, often twisty two lane roads. Combine that with the fact that Caravans and vehicles have grown in size and weight means they are even less suitable for these types of road.
Drivers - And people just can't overtake because usually they are in a convoy and leave no passing gaps and never seem to do the decent thing and pull over to let the queue pass. In the very North of Scotland a lot of the roads are single track - one lane both ways. There are verges labelled PASSING POINT. Do they get the message ? Nope.
And anyway, nobody but a lottery winner in the UK would think of buying a 4.1 V6 - all that wasted efficiency when you can have a 2.5 TD and get more torque and use galf the fuel
