I use to think that, but I swear every time I re-watch an episode of Justified I get a different perspective the second time around. Although she acknowledged that she tolerates Raylan because he's "Easy on the eyes" Rachel seemed more annoyed with Raylan getting to do whatever he wants pretty much and that's why she challenged him to get in the car. I also think she envies him and wishes that she could be the "rebel" of the marshals, but she can't really due to being a black female marshal in the south. (I believe she even says that almost exactly in an episode in the first season when she asks for Raylan's help when she has to go to Harlan for a case. She was afraid of not being taken seriously.) She plays by the book when handling cases, which is why Art always has her come to calm Raylan and Tim down, but she wants more than that.
As far as the panties comment goes, it could of been flirting, but I think she was trying to let Raylan and Art know that not only "whores" wear those kinds of underwear. lol
Plus, it kind of annoys me how they don't give her and Tim more screen time and more story arcs. Tim finally got one this season with Colt killing his military friend, but they have yet to really expand on that except for that one standoff in that "church". They threw a lazy reference to Rachel having a divorce, but that hasn't really paid off either.
Can't wait for next episode though. I can't believe there are THREE episodes left! My heart broke when that deal went south for Boyd and Ava. I knew it would, but I was still mad when it did. Johnny has to die this season.
Oh and does anyone know why Colt didn't stay around to collect the money from Leo Tonin's gangster friend after he saw the helicopter coming? I could've sworn Boyd told him to get his money.