I am very pleased with my Honda CRV. It is what I believe is called an intelligent 4x4. In normal driving it is Front Wheel Drive but if it senses that the front wheels are in bother it cuts in the drive to the rear wheels as well. The prop shaft connects to a unit mounted on the back axle. The propshaft and rear wheels each drive a hudraulic pump in that unit at the same speeds. Any variation in their speeds causes the 4WD to engage. I tested that out quite thoroughly in last years snow, the cut in was smooth and the car immediately corrected the spin and slide I had deliberately induced. There is of course no extra gear lever. My own CRV is a diesel and with that you only get a manual gearbox, but my cousin has the petrol version with an automatic gearbox and he is equally pleased with it. Size wise, I suppose it is middling - not as big as Range Rovers, Freelanders etc.