When selecting PE (Polyethylene) car covers, the material density (measured in GSM - grams per square meter) is the primary indicator of durability. For basic dust protection, a density of 80-100 GSM is sufficient; however, for outdoor all-weather protection, you should prioritize heavy-duty PE or PEVA blends exceeding 120 GSM. Ensure the material features a multi-layer laminated structure, typically including a UV-resistant outer coating and a soft non-woven or cotton inner lining to prevent scratching the vehicle's paintwork.