Welcome to Mia's Love Life. As you can tell, we analyze her relationship between her and Nash, since we all know Nash loves her. So, why not look at if she loves him back. I have proof that she does.
I believe Mia does care for Nash, more than a friend. Through her shy personality, she can make it look that way. Whenever there is something wrong with Nash, notice how she is usually by his side, and when there is something wrong with Mia, Nash is there faster than the blick of an eye. Here are some examples.
When Luna's evil song caused Jessica and Mia to be sick, if you her afterwards, she says
But Nash reinsures her, saying that he'll make he better, he promises. ^.^* How sweet!
When Nash betratys you and uses the lightning and trashes the engine, Mia knows and believes in him, since she knows he wanted to help everyone. If she didn't care about him, she would be along with Kyle and Jessica, wanting to kill him. And, when Nash puts everyone to sleep, after she slaps him, she admits, saying she loves him.
Also, after Nash betrayed them, in the game, I went around Vane and talked with others (It is pretty funny) and even Mia's mother can tell Mia likes Nash. =)
And at the end, when everyone leaves *sniff* Mia does say I love you, but she was saying that she loves all her friends...I dunno. You may never know.
Anyway, I'll get more stuff. If you have any info, especially from the Lunar; The Silver Star, please, tell me.