Trixie Tredwell Racer is the wife of Speed Racer Sr. and is the mother of X and Speed Jr. She is the sister-in-law of Spritle and Rex Racer. She became a main antagonist in the series after a car accident 16 years prior to the main series which resulted in her father, Tuffie Tredwell's death and her becoming permanently scarred both physically and emotionally. Even though Speed Sr. had tried to save him, she blamed Speed Sr. for her father's death. She inherited her father's multi-national corporation and began to use it's resources to help get even with Speed Sr., forming the Shadow Committee. To protect X ad Speed from her twisted influence, Speed Sr. was forced to take the boys away and go into hiding. However, after her sons went back in time to prevent the accident that made her the leader of the Shadow Committee, she returns to being the loving wife of Speed Sr. and the caring mother of X and Speed. She now lives happily with her family in the new timeline.
Trixie had an evil personality. She was very ruthless in her attempts to get world domination, which shines through when she had the Alpha Academy destroyed to hide any information about the Shadow Committee. She disposes people who had worked for her as soon as they are no longer any use to her, like with Zile Zazic when he failed to secure the mach 6 and with Handles Mustache, despite him being a loyal member to her cause.