If something happens, come forward and explain: voluntary surrender can cut a sentence by up to 40%, and minor offenses may qualify for more or exemption; “waiting out the prosecution limit” is a dead end

There is no cost at all. You can walk into a police station, stay on the scene and call the authorities, then tell them exactly what happened. The hard part is resisting the urge to “wait and see — maybe no one will notice.”

Article 67 of the Criminal Law: Surrendering voluntarily after committing a crime and providing a truthful account of one's crimes constitutes surrender. For surrender, punishment may be mitigated or commuted, and for relatively minor crimes, punishment may be waived. For those who do not surrender but provide a truthful account of their crimes (confession), punishment may be mitigated; if the truthful account avoids particularly serious consequences, punishment may be commuted. The sentencing guidelines issued by the Supreme People's Court and Supreme People's Procuratorate provide specific ranges. The benchmark sentence is the term calculated first based on the facts of the case, and the percentages below are reductions from that amount. Surrender can reduce the benchmark sentence by up to 40%; for relatively minor crimes, it can be reduced by more than 40% or waived according to law. In the case of confession, providing a truthful account of one's crimes reduces the sentence by up to 20%. Providing a truthful account of the same type of heavier crime not yet known to the judicial authorities reduces the sentence by 10% to 30%. If the truthful account avoids particularly serious consequences, the reduction is 30% to 50%. Pleading guilty and accepting punishment reduces the sentence by up to 30%. When circumstances such as surrender, significant confession, return of illegal gains and compensation, and compensation and forgiveness occur simultaneously, the reduction is up to 60%; for relatively minor crimes, it can be reduced by more than 60% or waived according to law. The statute of limitations is divided into four tiers according to the statutory maximum penalty: 5 years, 10 years, 15 years, and 20 years (Article 87 of the Criminal Law). However, Article 88 of the Criminal Law specifies exceptions. If the procuratorate, public security organs, or state security organs have initiated a case investigation, or after the court has accepted a case, evading investigation or trial is not subject to the limitations of the statute of limitations (Nationwide, China; the sentencing range has been in effect since July 1, 2021).

全国人大. 中华人民共和国刑法（经刑法修正案十一修正的整合文本）第六十七、八十七、八十八条. https://flk.npc.gov.cn/detail?id=ff808181796a636a0179822a19640c92；最高人民法院、最高人民检察院 (2021). 关于常见犯罪的量刑指导意见（试行）（法发〔2021〕21 号，2021 年 7 月 1 日施行）三（六）（七）（十四）. 甘肃省张掖市人民检察院转载全文. http://www.zhangye.jcy.gov.cn/info/1039/2086.htm；最高人民法院 (2010). 关于处理自首和立功若干具体问题的意见（法发〔2010〕60 号）一. 最高人民法院公报. http://gongbao.court.gov.cn/Details/f3089058d37e11cd16d801530934ae.html

The beneficiary of this item is oneself. Surrender is merely a mitigating circumstance; the crime will still be convicted, and the amount of reduction is determined by the court. The sentencing guidelines require strict control over the leniency range for serious violent crimes and drug crimes. Traffic accidents have a separate set of algorithms. Staying at the scene, saving people, and reporting to the public security organs count as voluntary surrender, but since these are already legal obligations, the leniency range must be strictly controlled. Surrendering after fleeing still counts as surrender, but the heavier statutory penalty tier will be used as the benchmark, and then the decision on whether to reduce and by how much will be made. What to do at the accident scene can be found in item 1 of this section (in case of a traffic accident, stop first, save people, and call the police). Hiring a lawyer first does not conflict with providing a truthful account; see item 5 of this section (hire a lawyer first when accused). What a lawyer helps you verify is whether the transcript is written correctly, not helping you fabricate a story.