The lightweighting of auto components is a crucial strategy for OEMs to achieve increasingly challenging CAFÉ requirements. Research from MIT has found that every 10% reduction in passenger vehicle weight reduces fuel consumption by about 7%. Since fuel economy requirements have already increased by 18% from MY 2012 to 2017, the weight savings strategies that are easiest to implement have largely been exhausted. Seating is the largest interior component by weight, but the foam is often overlooked from lightweighting consideration due to the perception that higher weight, higher density seating is an important aspect of the vehicle’s comfort. It has become almost a truism that the physical properties associated with seating comfort -- load bearing, resilience, durability - are directly related to foam density. A new auxiliary blowing agent known chemically as HFO 1233zd(E) is commercially available as Solstice® LBA. Using 2 -4 parts per hundred polyol has been found to lower weight in molded seating foam by10 to 20%, while maintaining properties related to comfort and durability. This hydrofluoro olefin (HFO) is liquid near room temperature (b. p. = 19C), non-ozone depleting, with GWP of 1, non-flammable (ASTM E-681), VOC-exempt by the EPA. Safe working conditions, well below the exposure limit of 800 ppm (TWA/TLV), can be maintained with the air exhaust systems commonly in-use in auto seating foam manufacturing. In VDA 278 testing, no residual Solstice LBA has been detected in the foam. In addition, Solstice LBA lowers the viscosity of the liquid polyurethane blend, improving foam flow in the mold. Better mold-flow assists intricate parts to be filled with less foam, providing a second pathway to weight reduction. Using small amounts of Solstice LBA with little or no reformulation can provide weight savings in intermediate sized autos of 1.1 to 2.1 kg.