Devils Advocate Here!
So, European towing standards ARE NOT based on engine size, driveline limitations,
brakes, carrying capacity etc., just total
weight???
I think, to a degree, that towing limits are also controlled by the fact that high MPG requirements put vehicles closer to maximum capabilities, thus reducing towing capacity, as is evidenced by the huge hits that towing puts on high MPG vehicles.
Add to that, most American built RV trailers are simply no longer in the size and
weight category that they can be towed by the average American or European compact to midsized vehicle, and car makers sure aren't going to build a right sized vehicle for us, the 1%er's of the RV market.
But Wait..... What about that midsize pick-up that GM just reintroduced?????