I don't know if any car comes stock with them, but I think there a good idea if you replace p/s parts and the new or rebuilt ones might have residual metal filings and such.
Funny you mention this, its been a running joke at my work because I was on the phone with one of our shops (customer) techs and I asked if he might want one- his response was "yeah, and I'll change your muffler bearings and bleed your chassis fluid for ya."
But, they do exist and I recommend you get one of the canister style ones with a magnet and filter inside instead of the pen-sized filter that you shove up the return hose- seriously thats how it works.
