the obvious answer to all this is to buy an old 4x4 banger and keep it going forever with transplants etc until the MOT emissions tests gets you.
Seriously though, I would argue that unless you live on a farm or up a mountain, you dont really need a 4X4 anyway. If you do, you dont need a 4 litre one either unless you are carting stuff across fields. For the caravanning brigade something like a CR-V or X-Trail or even some decent sized MPVs now come with reasonable fuel consumption and lowish C02 emissions. I've got a C-Max which happily tows up to 1500kg and my brother owns an S-Max which will manage 1700kg both cars are in the less than 169gm/km category.
Its not just 4x4s that are being targeted (although they use more fuel and have higher emissions because they are heavier and the transmissions are less efficient) it also includes big engined thirsty cars as well. .
I don't agree with the taxes but I also fed up with all the moaning that they are targeting big cars either - most people don't need a big one, they just choose to drive one. No one really needs a car of over 2 to 2.5 litres, so if you've got a big one in a lowish tax band, keep it forever and only buy a 1.2 litre roller skate to keep the chancellor happy.
On the subject of ever increasing and unfair tax increases I haven't yet heard of much sympathy for the poor boating community who are facing a potential doubling in the cost of red diesel. Again, if you've got a big engine and want to roar up and down rivers or the sea then that's tough, don't complain, get a smaller engine and then you'll use less fuel.
It's the bloke who lives on a narrow boat who needs it for heating and propulsion that I feel sorry for coz it's his home that being targeted - that could really get me on my soap box.....