Jason@nospam.com (Jason) wrote in message:

I have two or three car wash self-serve bays near my home and school
in central New Jersey.  I use them so much I keep them in business,
especially during the summer.

In addition to Jason's advice to spray down the car once a week, wax or
no wax, I also make it mandatory to manually spray down my Accord
immediately on my drive home from every single day at the beach.  
This spray-down removes the small salt particles that are deposited onto
the car's finish during the day, and cling to the finish through
static electricity, so that the particles do not get blown off even
when driving 65 mph.

As those who live in coastal towns can attest, salt air is very detrimental
to a car's finish, especially if the car is ungaraged.  Salt is simply
sodium chloride (NaCl).  When dew forms on the car during the following
morning, the water reacts with the sodium chloride (in the presence of
sunlight, which catalyzes the reaction) to form hydrochloric acid (HCl)
and sodium hydroxide (NaOH), which are both extremely damaging to the
car's exterior surfaces, particularly the hood, roof, and trunk.  Thus,
a spray-down is highly recommended for everyone immediately after any
day at the beach.

Paul