The flirt, the tomboy, the sexy bishi - Haruka is a very appealing character within the series. Her personality is two-fold: one side is very playful yet conflicted; the other, stern and devoted. So why is page called "inferiority complex?" I'm glad you asked!. An inferiority complex is "a feeling that one is inferior to others in some way."[1]. Stop Depression Today.com states 7 signs of the complex; I think Haruka fits 3-4 of these.
Haruka comes into the picture as person with boyish good looks and exceptional racing ability. In Episode 92, she plays a racing game with Aino Minako, letting her get a head-start before Haruka leaves her in the dust. However, she can be a modest individual in front of a crowd. When Haruka completes a test-run before a crowd of 
adoring fans, she modestly compliments the machine's capabilities above her own.[2] You gotta admire a woman who knows when to be a little selfish and when to give respect.
Nevertheless, Haruka has an interest in "tricking" other people. She is commonly confused for a man yet doesn't feel the need to correct people; she doesn't seem to like confessions. This seems to tie into the her complex's "sensitivity to criticism" and "hypercritical attitude." She possibly enjoys hiding under a facade because she recognizes her own shortcomings. This allows her to feel safe and competent if she is criticized since they couldn't be attacking her personally.[1] Haruka once explained how she liked "run from her destiny" and be free.[3] Perhaps her disregard for the truth (a.k.a LYING!) is her way of going back to that time when she was free to do as she pleads. She can stray a little from her path and engage in some old-fashioned tom-foolery.
But Haruka's biggest characteristic is her flirtation. She is probably the biggest flirt you'll ever meet! In both versions of BSSM, but especially in the anime, she uses her good looks and charm to attract many young girls. Minako, Usagi, and Makoto are her biggest victims. Her winks, smiles, touches, and gestures all send the right signals to them, thinking that "he" likes them. An "inappropriate response to flattery" perhaps?[1] It has caused a few mix-ups and mishaps (such as Minako and Usagi's stalking).[2] Haruka takes a special interest in Tsukino Usagi, eventually butting heads with the likes of Seiya Kou and Chiba Mamoru.
Haruka's more mature and serious side is definitely evident in the manga. She becomes determined and irritated. In Act 24, she scolds the Inners for interrupting them and endangering their mission; if they get in the way, she won't hesitate to take care of them. Even though Haruka may enjoy a little time away from her mission that does not mean she isn't devoted. As Sailoruranus, she is willing to give up her life to complete her mission.
Haruka does have a very likeable personality and could easily make many friends. I believe she does want to have that kind of security, but she knows that she cannot get 
attached too easily. This could be attributed to a "tendency toward[s] seclusiveness and timidity."[1].
Haruka's complex rears its head when she is competing; she comes off a little win-happy Act 25 shows a little of her competitive side. She challenges the Inners to a little judo practice after Kino Makoto said they were "training" on the mountain. Makoto takes the offer, but is almost immediately slammed down to the mat. Minako scolds Haruka for hurting women, but Haruka replies that "if a girl can't beat a boy, don't you think she deserves it?" Haruka definitely has some kind of issue with strength and male dominance. Perhaps that's also a reason why she dresses and mimics the mannerisms of a man. Could she be proving a point that women and be on the same level as men?
Haruka is indeed a very complex character. She enjoys a little flirtation here and there but has a powerful devotion to her "important mission." Does she really have an inferiority complex? Maybe not the point of low self-esteem. But I do think it helps to address some of her distinct personality traits. Plus it's a great way to draw your eyes to this page!
1 Seven Signs You Have An Inferiority Complex. Stop Depression Today.com.
2 Act 24. Infinity Arc. Sailormoon Manga.
3 Episode 106. Super Season. Sailormoon Anime.