I use a non silicone car wash solution with warm water and a thick paint brush then wash off with a gentle stream from a hose. Wipe off and that's it. For anything stubborn I use all purpose cleaner (alcohol content) sparingly then gently hose off. Micro fibre cloths, finished with poor boys polish (body panels). Wire wheels; brake cleaner spray and a small plastic brush, followed by soapy water and a hose off (long and sometimes painful process). Although my seat is plastic, I use a bees wax polish on it, which leaves a good no shine finish to the plastic. I use Meguires plastic conditioner on the other black plastics. It's always a labour of love but I see it as a bonding activity.