bleedsoff wrote:How often does a car need to be cleaned these days?
as often as you want it to be bleedsoff! if it isn't dirty don't clean it

if you aren't doing it yourself then monthly or bi monthly would probably suffice (unless you are partiularly car proud & your wallet can stand paying for a detailer every week or fortnight)
Getting a detailer to go over your car you would be looking at probably £30-50 for a wash, wax & hoover (with a pre wash/snow foaming stage in there too)
it depends on how much you wanted doing (just outside or inside aswell) & what in the way of products you wanted using, it also depends on the size of car & how dirty it is.
[prices taken from a guy who works local to me who I consider roughly middle of the road & a reasonably comprehensive website found through google]
NB: both websites used for prices offer maintenance programs from ~£30/month so if you find someone local you are happy with see if they offer this sort of service
there are certainly a few owners who don't have parking & just hoik buckets of water out to the road & clean it out there though so its worth considering, cars will drive past it regardless.
alternatively there is always the guys with a bucket & pressure washer down the road somewhere or car wash it depends what you want to keep up with and can afford in the long term
hope that gives some thoughts, i'm not sure if T & J offer a maintenance program to offer some more comparison prices
S