Yes it is a shame that the RMP, RAFP, RNP & MODP in the UK are primarily stuck with civi patrol cars, but they don't really need large military vehicles for domestic use. I've seen quite a few RMP cars whilst working in London recently over the Olympics, I assume to police the large military presence in London for security, but I have to admit that it does look a bit wrong when you see the redcaps drive around in a little Vauxhall Corsa.
Not currently available, but if BMW made a small van vehicle based on the 5 series touring: