If you only detail twice a year, pick late spring and early fall. Each protects your car against the season that follows.
Late spring
By May, the heaviest pollen has fallen. A full detail removes the yellow film, cleans the cabin air path and resets the car before the summer heat.
Early fall
Before the leaves drop and the roads get treated, a coat of protection helps paint resist sap, tannin stains and brine. Clean the interior now and it is easier to keep clean through winter.
What about summer and winter?
Both are good for a quick exterior wash. Heat bakes contaminants in faster, and winter brine is worth rinsing off even on cold days.
Related