Tennessee v. Garner the Supreme Court said differently.
Law enforcement officers
pursuing an unarmed suspect may use deadly force to
prevent escape only if the officer has probable cause to believe that the suspect poses a significant threat of death or serious physical injury to the officer or others.
Tennessee v. Garner - Wikipedia, the free encyclopedia
Imminent threat is the standard for civilians, not police.
The standard for police is Tennessee v. Garner.
I'd say that the assault in the police car, if accurate, meets the standard.