There was no way for Clark to get out of telling Lois his secret once she started questioning him about it, but telling her while they were in the car wasn't the best idea. There was no way she was going to believe Clark was an alien with special powers without proof.
Even though things didn't go well during their conversation, it's been one of my favorite parts of the story so far.
I'm looking forward to finding out happens next and who is calling Lois.
