Trixie often flies around in a helicopter during a race, acting as Speed's spotter, a function she also serves in the live-action movie version during the Casa Cristo 5000. In the manga, it is mentioned that her father is the president of Shimura Aviation, which explains why she has her own helicopter. To add comic relief in the anime, Trixie becomes jealous if Speed pays too much attention to another girl or if she feels ignored.

Unlike most female characters in cartoons at that time, Trixie is not portrayed as a helpless perpetual victim. Trixie often proves herself the equal of Speed when forced into physical altercations. While Trixie has been captured on occasion by the villains, she refuses to cower or plead for her release, more often giving the bad guy a serious tongue-lashing until she is either rescued or escapes on her own. On some occasions, Trixie has even been the one to rescue Speed or other male characters from their predicaments. In the spin-off Speed Racer: The Next Generation, she is assumed to be the mother of X and Speed Jr.

Usually arriving in her helicopter, Speed's girlfriend Trixie is always ready to help Speed in times of crises. Whether performing search-and-rescue missions, or smoke-bombing Speed's adversaries, Trixie never backs down in the face of danger. And, like Racer X, she happens to arrive just in the nick of time. She isn’t afraid to speak her mind, either to Speed, or to any of the villains she comes up against.

Known to throw more than one surprised criminal for a loop, she'll do it again if fools cross her path. Loyal and protective, Trixie is direct and clear to Speed's female oglers and to other heads of state (who wish to betroth their daughters to Speed) that he is taken. After all is said and done, Trixie usually gets her way – even if she has to stow aboard the Mach 5.

(Source: Speed Racer Wiki)