Do Not Panic
It’s easy to get overwhelmed while writing. For every question you’ve managed to answer, two more are unanswered. I’m going to help you out and remind you of a wonderful truth about writing – there are no wrong answers.
Why was your character interested in the black Sedan? Make up a reason. Either someone is tailing them, the character likes Sedans, or the vehicle reminds him of something. Pick one and move on. Even if it sounds ridiculous, you will be surprised how it satisfies your characters. It will even pacify you for a bit.
Write the answer now. If it feels wrong, mark it and recheck it in December. If it feels wrong then, change it. If not, keep it.