This paper details the control system development process for the University of Washington (UW) EcoCAR 2 team over the three years of the competition. Particular emphasis is placed upon the control system development and validation process executed during Year 3 of the competition in an effort to meet Vehicle Technical Specifications (VTS) established and refined by the team.The EcoCAR 2 competition challenges 15 universities across North America to reduce the environmental impact of a 2013 Chevrolet Malibu without compromising consumer acceptability. The project takes place over a three year design cycle, where teams select a hybrid architecture and fuel choice before defining a set of VTS goals for the vehicle. These VTS are selected based on the desired static and dynamic performance targets to balance fuel consumption and emissions with consumer acceptability requirements. The UW team selected a Parallel through the Road hybrid architecture due to its combination of performance capabilities, high power path efficiency, and reliability due to separated electric and biodiesel powertrains.Over the course of the three year competition, the controls team developed a number of primary operating modes and strategies to control these powertrains. The different modes are examined in detail, along with how various software testing methodologies were used to validate the safety and performance of the vehicle in simulations. Key improvements in Year 3 are examined, in addition to investigating their effects on the vehicle's ability to meet VTS goals set by the team. Many validation tests were conducted using dynamometer testing at Argonne National Labs, which showed that the vehicle would be able to meet the majority of VTS goals during the Year 3 Competition Dynamic Events.