In that case, I've no idea if and when ethanol is added at Stanlow. All refined gasoline will have to be approved by the lab before it leaves Stanlow. This is fairly straightforward if you are only supplying for one customer but if you are supplying 5 or 6 customers with different specifications it means extra storage, extra lab technicians and higher costs. It was industry standard when I worked there for U.K refineries to distribute exactly the same stuff to different petrol stations, it may have changed but I somehow doubt it.
Pete
Maybe the different ingredients only exist in the marketing brochures?