FISA had introduced new fuel economy rules aimed at reducing speeds, ruling that cars powered by turbocharged engines would only have 220 liters of fuel per race, with re-fueling now banned (the tank had to be 220L, but teams were free to try and squeeze more in if they could, which some tried with methods such as freezing the fuel inside the tank). TAG, while still a sponsor with Williams, became a partner with McLaren team boss Ron Dennis, and commissioned German sports car manufacturer Porsche to design and build what would become the TAG-Porsche V6 turbocharged engine. Porsche had extensive experience with similar economy rules due to its participation in endurance racing (which included the 24 Hours of Le Mans) and this translated in superior fuel economy. Coupled with the superior aerodynamics of Barnard's MP4/2 (especially at high speed), this made the McLarens almost unbeatable in races throughout the season.