Whose insurance is responsible if a car was in the process of being sold title signed over and bill sale dated prior to event new owner leaves gear it rolls hits another?

The insurance responsibility in this scenario depends on the specific laws and regulations of the jurisdiction where the accident occurred. Generally, the insurance of the new owner would be responsible for covering the damages caused by the rolling vehicle, as they are considered the legal owner of the car at the time of the accident.

In some jurisdictions, there may be a grace period during which the transfer of ownership is processed and the new owner's insurance may not yet be in effect. In such cases, the insurance of the previous owner might still be applicable until the transfer is complete.

To determine the exact liability and insurance coverage, it's important to consult with the local motor vehicle department and seek legal advice if necessary. The specific circumstances of the case, such as the exact timing of the title transfer and the laws governing vehicle ownership and insurance, will determine whose insurance is responsible for covering the damages.