If my neighbor is claiming that I hit his truck over 3 weeks ago but ran off and hasn't filed a police report, isn't it too late for him to file one now?

Technically it is not too late for him to file a police report, but what evidence does he have to back up his claim?  I would think at this point, with no evidence, no damage and nearly a month later, the police would not take a report from him very seriously.  You cannot prevent him from making a report, but realistically, how much further could he pursue the matter?