With the help of Elf and Ford, Tyrrell moved to Formula One in 1968. He started as a part of Matra International. It was made up of Tyrrell's own team and the French auto maker Matra. Stewart was expected to race very well. He won several Grands Prix in the teams Matra MS10. The car's most unusual feature was the use of aviation-styled structural fuel tanks. These let the car to be around 15 kg lighter. Although it was lighter, it was still stronger than the cars it was racing against. The FIA thought that the technology was not safe. They chose to not let it be used in 1970. They said that rubber bag-tanks had to be used instead.