You can detain the car because of the need to collect evidence, not because of the need for compensation. Appraisal shall be entrusted within three days after the end of the accident site investigation, and the inspection and appraisal period shall not exceed 20 days. More than, should be reported to the public security department for approval, the longest shall not exceed 60 days.

Within 5 days after the inspection and appraisal results are determined, put the car.

According to the Regulations on Procedures for Handling Road Traffic Accidents

Twenty-eighth because of the need to collect evidence, the traffic administrative department of the public security organ may detain the accident vehicle and motor vehicle driver's license, and issue a certificate of administrative compulsory measures. Detained vehicles and motor vehicle driving licenses shall be properly kept.

The traffic administrative department of the public security organ shall not detain the goods carried by the accident vehicle. After verifying the weight, volume and loss of the goods, notify the driver of the motor vehicle or the owner of the goods to handle it by himself. If it is impossible to notify the party concerned or the party concerned fails to handle it himself, it shall be handled in accordance with the relevant provisions of the procedures for handling administrative cases by public security organs.

Thirty-seventh need to carry out inspection and appraisal, the traffic administrative department of the public security organ shall entrust a qualified appraisal institution to carry out inspection and appraisal within three days from the end of the accident site investigation. Autopsy shall be entrusted within three days from the date of death.

If inspection and appraisal are needed within three days after the on-site investigation, it shall be reported to the traffic management department of the public security organ at the next higher level for approval.

Article 38 The traffic administrative department of the public security organ shall agree with the inspection and appraisal institution on the completion period of inspection and appraisal, which shall not exceed 20 days. For more than twenty days, it shall be reported to the traffic administrative department of the public security organ at the next higher level for approval, but the longest period shall not exceed sixty days.

Forty-fourth within five days from the date of the conclusion of the inspection and appraisal, the traffic administrative department of the public security organ shall notify the parties to collect the detained accident vehicles, motor vehicle driving licenses and detained articles.

If the driver escapes by driving an ownerless vehicle or fails to collect the vehicle after 30 days' notice, the detained vehicle shall be dealt with according to law three months after the announcement.

It can be seen that the public security traffic control department can detain the vehicle only for the need of collecting evidence (such as speed, whether the brake lights are qualified, etc.). ), but not for the need of compensation, it should be seized through court property preservation procedures. The inspection and appraisal time is generally not more than one month (the specific situation can be shorter). Within five days after the inspection and appraisal, the traffic administrative department of the public security organ shall notify the parties concerned to collect the detained accident vehicles, motor vehicle driving licenses and seized articles.