my advice..

Park far FAR FARRRRR away from supermarket parking places...
keep it clean as much as you can...

Use a microfibre mit and buffin clothes... (they are the Shit)

i got myself a new Autoglym chamois and im in love =D its got holes and sucks up the water well even on the first go...

Refer to link =D
AutoGlyme Aqua Dry