When most people watch Cars they talk about Lightning and Doc’s Father-figure like relationship…But Flo and Sally have a mother-daughter relationship…That’s pretty interesting… 
I think Flo was too minor in the first movie for that, but who knows. If Mater can be the main character, then maybe something like this could happen.
To me they seemd liked just friends.
But Sally did say that Flo took her in…which seems motherly…
i’m a die hard cars fan but it’s really annoting how they’ve made mater the main character!!! i love him n all, but, really? NINE shorts about him? an entire second movie with HIM as the top character??? 
IT"S GETTING OLD< PIXAR! we wanna see more sally and mcqueen, not hillbilly-without-a-hood!!!
Where have you been all my life 
?!By the way just so you know theyre’s already a topic about this… 
Hey! I’m newbie so please forgive me if I do anything noobish but I would like to join the discussion 
OK, so ON TOPIC: I totally agree. I can see a mother daughter relationship about them. Unfortunately I wish they had went a little bit more in depth about Sally’s previous life but hey that’s just me wishing. I don’t know what it is but I can see where you are coming from on that. And…OFF TOPIC I agree 100% on the whole Mater taking over issue. To me this is how I felt from the first movie: Main character: McQueen. Prime Secondary characters: Sally, Mater and Doc. BUT for the sequel looks like it’s gonna be: Main: Mater and McQueen, secondary: other new characters. No Sally!!! 
I’m kinda disappointed Sally is taking a backseat in this movie, and it’s one of my main gripes about Cars 2. But who knows, Pixar may prove us wrong. Nothing is confirmed till we have actually sat through the film in theatres, so there’s always hope Sally will have a few great scenes with Lightning… wink
Anyway, to get back on topic… yes, I didn’t see it that way before, but now that y’all have mentioned it, Sally did mention that Flo took care of her when she first arrived. Flo also seems to take an interest in Sally’s affairs (“Is that what ah think it is?”), but it could be her just being a nosey busybody. 
But yeah, I could see Flo and Sally having a mother-daughter relationship even though they’re friends, much like Lightning and Doc, and Gibbs and Abby (of NCIS, a favourite show of mine).
It’s really sweet, and it adds more to the characters if Pixar intended it that way.
I love the part where Sally invites McQueen on the drive and Flo knows that McQueen won’t run and take off. She just has that instinct you know?