Every sentence begins with a capital letter. It is not optional. We don't leave a space before punctuation.
Sajid1234 what is the difference between they could come by car, and they might come by car ?
The difference is what it always is between "could" and "might". If they could come by car, they are able to, or it is possible that they will. If they might come by car, it is possible that they will. The meaning "they are able to" is obsolete, but you will see it in older writing.
~ they would be able to (so maybe they will)
~ maybe they will
They are similar.