In 1981, McLaren merged with Ron Dennis' Project Four Racing; Dennis took over as team principal and shortly after organised a buyout of the original McLaren shareholders to take full control of the team. This began the team's most successful era: with Porsche and Honda engines, Niki Lauda, Alain Prost, and Ayrton Senna took between them seven Drivers' Championships and the team took six Constructors' Championships. The combination of Prost and Senna was particularly dominant—together they won all but one race in —but later their rivalry soured and Prost left for Ferrari. Fellow English team Williams offered the most consistent challenge during this period, the two winning every constructors' title between and . However, by the mid-1990s, Honda had withdrawn from Formula One, Senna had moved to Williams, and the team went three seasons without a win. With Mercedes-Benz engines, West sponsorship, and former Williams designer Adrian Newey, further championships came in and with driver Mika Häkkinen, and during the 2000s the team were consistent front-runners, driver Lewis Hamilton taking their latest title in .