I have been under the Pacifica and had the rear wheel well liners off. There is no factory undercoating on the Pacifica. Just a grey finish coating. In fact, in the rear wheel well, there is a 2-3 inch wide strip of metal body panel between lip of well and the plastic liner. This area appears vulnerable to rocks and road grit damaging the zinc/primer (?) coating and causing rust to set in prematurely. I decided to apply undercoating to that area myself as a preventive measure.