Uder fender liners
REALITY--the regular use of an E-9 on any wet, snowy, chemically treated, or salted road used to get rid of snow & ice will easily defeat the fitting of the panel or the Volvo liner mentioned that you are considering or planning to install.
Road silt will always find its way around, under, beside, above, wherever to defeat the intended positive purpose of the liner/barrier that you are expecting--and with moisture added you are in for silent corrosion commencing again. When new--in all E-9's there was originally a panel fitted to prevent same and in time it effectively served to hide the enemy--silt--lurking in the crevices behind the panel that will do its damage--and ALL of them did--just ask Coupeking or Carl Nelson---aka Bimmer Doc what the7y have found--as each or collectively have more first hand Coupe experience here in the western USA than any two I know.
Whenever driven in the conditions previously mentioned--even in SoCal where we don't have snow or salts or chemicals on the roadway--except from auto fluids dribbled about--yet the accumulation of silt with moisure added by un-witting hose wielders washing their Coupes--or splashing thru puddles from irrigation (we have a lot of that here) or from infrequent rains will still do the damage--I speak from first hand experience with two Coupes including the BLUMAX that experienced corrosion damage until his owner/caretaker wized up. Just my input based on actual experiences!!
