Thanks to all who replied. These were great suggestions. I'll be ordering Griot's Speed Shine....and NoRinseWash& Shine tomorrow.

I'll probably drive down the Do-It-Yourself Quarter wash....I'll take my old Toyota down first to test it out. When I take the Cayman down, I'll definitely use my own car shampoo. I need to learn how to use the hose so none of their car wash comes out.

One question about those Do-It-Yourself washes. I do want to do a mid to late December washing before putting the car to bed for the winter. Can you safely wash the car when the temperature is cold? I presume the water is cold too at those places. Is there any cut-off for cold temperatures?