A painted surface is slipperier than a non painted
surface... BUT paint adds weight.. why do the
hot shot NHRA & NASCAR run painted surfaces.. they
also need a place to advertise but the weight of
the paint is also added into the total weight.. if
I recall correctly a paint job on a car my size
was 50#.. a full size can be as high as 100#
EDIT
Dollar VS dollar it is was more expensive to just
do a bare paint job.. if your talking no body
filler.. but even if you do a bare metal your
still gonna have to spray a clear to protect the
metal so its not truly a paintless job