Abstract: Various plastic structures for automotive applications are disclosed. The plastic structures are preferably produced by blow molding and comprise at least one cavity, generally for containing a vehicle component therein, formed within the confines of the wall structure. Exemplary applications of the plastic structures include various fluid reservoirs located in the engine compartment (e.g. along the fender inner panel, the wheel well liner, the underside of the hood, the cowl, the firewall, and the front-end structure), the passenger compartment (e.g. rear shelf, door arrangements), beneath the vehicle (e.g. fuel tanks, spare tire holders) and alongside the vehicle (e.g. step platforms).