4 ft of water is not a trivial depth for any vehicle. I honestly don't know of any stock SUV that can even come close to that depth, even the military humvee's are only rated for 2.5 ft in stock form. I know it can be done with a lot of money and time, but it's not something you want to try out on your new LR2. I've seen cars go through that depth, but while you may only see an extended air intake, it's the "other things" that you don't see that make all the difference.
You seem to be really fixated on buying a Land Rover and driving it through deep water. All I can say is, don't believe everything you see in the advertising. If you really plan on driving through water that deep, you'd better have a really good insurance policy, because the LR will not survive. I don't know how to put it any simpler than that.