The Mercedes F1 W05 Hybrid, originally known as the Mercedes F1 W05, was a highly successful Mercedes-Benz Formula One racing car designed and developed under the direction of Bob Bell, Aldo Costa, Geoff Willis, Loïc Serra, Russell Cooley, John Owen, Mike Elliott and Jarrod Murphy to compete in the 2014 FIA Formula One World Championship. The cars were driven by 2008 World Drivers' Champion Lewis Hamilton and Nico Rosberg, both of whom remained with the team for a second and fifth season, respectively. The F1 W05 was designed to use Mercedes's new 1.6-litre V6 turbocharged engine, the PU106A Hybrid. The chassis was named "F1 W05 Hybrid" to represent the fifth Formula One car that Mercedes had constructed since 2010, while the hybrid was marked to recognize the utilization of fully integrated hybrid power units. The car made its competitive debut at the 2014 Australian Grand Prix, the opening round of the 2014 season. After participating in 18 rounds of Grand Prix racing, the car made its final competition appearance at the season finale race – the 2014 Abu Dhabi Grand Prix, before retirement. As the first Mercedes F1 car of the hybrid era of the sport, this was the car that kick-started an unparalleled period of dominance by Mercedes in the sport that lasted for eight years, delivering 81 Grand Prix wins for Hamilton, 20 for Rosberg (until 2016) and 10 (from 2017) for Valtteri Bottas.