You pass the information on to your insurance company and they will pursue it on your behalf. As you have a witness (did you get their name and address?), then it should be okay and the police can go round and follow it up by checking his car for damage. HOWEVER, you have to act quickly, to stop him from having a chance to repair HIS damage before the police view his car. So first port of call is to PHONE the police local to the incident and get a crime reference number, then phone your insurance company and provide this to them and see if they will give you his address details to pass on to the police. However, try and do everything you can yourself in fact finding, so that you can pass all the information back and forth first hand. If you leave it to them to do everything, then time may pass before they do so, sufficient for the culpritt to repair his car and cover up the accident. So you need to express to everyone, how time is of the essence. Use the fact with the police that they ran over your wind-breaker, and only TIMING prevented the pair of your from either being serious injuries or even death .