Just had my white GS300h Fsport professionally detailed by a master detailer in Luton. He used Gtechniq Crystal Serum which when applied professionally gives you a seven year guarantee so long as you go back for an annual "checkup". The end result is that rain and road muck just slides off the paintwork and very little ongoing maintenance is required bar hand washing with 2 buckets.
While it is expensive, around £900, as I plan to keep the car for 7 years or so, the annualised costs are not so bad, oh and by the way
The car looks AMAZING!!!