Thirteen car interior cleaners, priced from 36 cents to $1.25 an ounce, were
applied to identical panels of brand-new polypropylene, the plastic used for
most dashboards, door panels, consoles, and trim. Each panel was then
measured for gloss at three spots, for slickness by the force needed to drag
a sponge under a 5 lb weight across it, and for color change with a
colorimeter. Untreated new plastic set the baselines: a gloss score of 3.6,
2.9 lb of sponge force, and a color score of 20.39.
Dust attraction was tested by treating a fresh panel with each product,
covering it in dust, and measuring what remained with the colorimeter,
against a water-only panel that scored 37.42. A sugary coffee drink was then
sprayed on the panels and left to dry in the sun until a sponge needed
11.8 lb to move, and each cleaner got two rounds of three trigger pulls and
a wipe before the sponge test was run again. Spray output per trigger pull
was weighed over ten pulls, and water repellency was rated on a
side-by-side spray, assessed subjectively.
Gloss and color were left out of the final ranking as matters of taste. The
four graded tests were slickness, dust, the change in slickness after the
coffee cleanup, and water repellency, and they split the field cleanly:
several products that added shine or a rich finish also turned the panel
slick enough to matter on a steering wheel, and most of those same products
attracted more dust than plain water.