The global automotive industry is currently undergoing significant changes and the companies are not only faced with opportunities, but also with new risks. Traditional automotive industry giants are fighting to maintain their market share and their profitability, and at the same time Asian automotive companies are increasing their share of the market and their profitability at high rates. Motivated by the situation in practice and by the Toyota development process, Daniel Sörensen examines the question of how much to invest in pursuing more than one design alternative in parallel within the product development process. He develops a real options model capable of modeling and valuing in monetary terms the effects of interproject correlation coefficients and volatilities in order to compute the optimal number of design alternatives to develop in parallel. Based upon economic theory, he presents five principles in order to value-maximize the product development process.