I used 3M 08868 on the quattros sills, expensive at 12 quid a tin ( or thereabouts) but gives a very good finish. The part number above is for the black product.
Just go into you local VW or PEUGOET parts dept and ask for under body stone chip for any model they make.It comes in 1 liter cans so you can put it on with a shuzts gun.