Commodity guide · auto parts
Boxed auto parts commonly rate class 60 - 85 depending on density; dense palletized parts can reach class 65 or lower, bulky sheet-metal panels rate higher.
Auto parts span the whole scale because the category does: a pallet of brake rotors is dense enough for class 60, boxed mechanical parts often land at 22.5 - 30 pcf (class 65) or 15 - 22.5 pcf (class 70), while bumpers, fascias and body panels are mostly air and can rate class 125 or above.
Worked example. Two pallets of boxed mechanical parts: 2 × 48 × 40 × 30 in, 620 lb each. That is 66.7 cu ft and 1240 lb → 18.60 pcf → class 70. Run your own numbers →
Rate the shipment you are actually tendering, not the category. Mixed pallets of parts should be measured as loaded; a single light panel in a big carton will drag the whole pallet's density down. Engines and transmissions are dense and usually rate well - see the dedicated pages.
Related: the full class chart · density calculator · how NMFC codes work.