From what I've read, the plan doesn't seem to be very well developed. Apparently it's not meant to cover all cars so which would be affected and which not? What do they mean by 'Chelsea tractors'? Is it all 4x4's or only those above a certain weight? Would it also include four wheel drive saloons or big 2 wheel drive SUV's, too? It seems that someone has thrown an idea into the discussion without giving the issue much thought. It's a case of someone opening their mouth before they switched their brain on.
On the other hand, with the ever increasing weights of caravans, we will be forced to abandoning the 85% weight ratio recommendation in the not too distant future. The technical means to increase the figure up to, say 100%, without compromising safety are available. The caravan and car industries will just have to put them into practice.