I have the same issue as you as I personally owned a white FD2 and I know the pain that you have been facing while maintaining you car. A white car or light color car will definitely need more time to take care with. Initially, I thought the same way as you do, in order to keep my car in tip top condition, I try my ever best to remove all the dirt and stains every time I wash my FD2. Claying is not for routine maintenance as most of the 'Guru' advised we only do Claying twice a year. Of course the best and "kiam siap" ways are without re-coat Permanon Platinum again. I can remove most of dirt or stains or even minor road tar as you described above by using the BrilliantShine Shampoo for routine maintenance, dilution is 0.25% (5ml BrililantShine Shampoo with 2 litres of water). I agreed that sometimes we might need to scrub to remove certain stubborn stains or dirt, but please make sure you use a wash mitt or microfiber cloth that will not create swirl marks, NOT your finger nail. I always keep the affected area with diluted BrilliantShine Shampoo while cleaning on it to minimise the chance of creating swirl marks. I suggest you to perform a full surface preparation before you apply Permanon Platinum and you should be able to remove the said dirt and stains during your routine maintenance. Zerosp will be able to guide you from A to Z.

Thanks.