So, since the show started they've never found out who tried to run her over. It could have been a scared driver that hit her, panicked and ran for it, who knows?
But here's MY theory: I think it was Dina who ran her over. She shows up at the hospital when Samantha got hit even though they apparantly haven't been friends since 7th grade. :/ Hmm....THEN Dina mentions that for 'some reason' her car can't drive over 50mph. To me, that sounds like something happened to the engine, ja? And finally, the obvious resentment that Dina shows every now and then towards Sam.
What do you guys think?