Advances in process and catalyst technologies have led to the development of a new family of in-situ or thermoplastic olefins (TPOs). These materials are produced in a multiple polymerization reactor system with an ethylene / propylene rubber content over the range of 20 to 56 wt.% and flexural modulus levels ranging from 200 to 1200 MPa (30,000 to 175,000 psi). In addition, these materials have demonstrated excellent paintability, adhesion and abrasion resistence. They have successfully passed the GM 4388M schedule of testing for painted materials, the GM 9911-P ‘Scuff Resistance Test’ and the Ford Motor Company ‘Thermal Shock Test for Paint Adhesion’. This paper discusses the production, physical properties, end uses and cost benefits of in-situ TPOs developed using the BASF/Quantum vertical stirred bed gas phase polypropylene process.