Re Towing with a 316 compact
I too would like a tow bar for my 316i compact mainly to tow a trailer to the tip or builders yard, but do not want to cut the rear spoiler. I would say however that in my experience of other cars it should be able to tow light loads. The website uktow.com states that a 316 or 318 can tow 1400kg or 3086lbs so that's way over a ton! nearer a ton and a half.
As an aside I once towed a sailing dinghy to Devon from Manchester with a 1275cc MG MIdget with no problems with a measly 72ft lbs torque and about 56BHP. Coming back the boat contained about 6 gallons of scrumpy cider. Well ther's no where else to carry so much in an MG Midget!
I've also towed my speedboat (not sure of weight but probably way over 1/2 ton) in the days of waterskiing on Windermere with many cars from an MGB-GT 62 ft lbs and 88 BHP, to a Chevrolet Camaro Z28 5.7 litre V8 325 ft lbs and 285 BHP. Now that was a great tow car and she didn't seem to notice the boat was there! 0-60 spec' is 5.8 seconds so probably sub 8 seconds with the boat! Not that we did that of course. :hihi