The California cops who killed a 21-year-old aspiring rapper sleeping in his car unleashed 55 bullets at him in 3.5 seconds — in an incident deemed “reasonable,” according to a report commissioned by the Vallejo City attorney.

The report from paid consultant and retired Livermore police officer David Blake concluded that the Feb. 9 killing of Willie McCoy was “in line” with current use-of-force practices.

“The 55 rounds fired by 6 officers in ~3.5 seconds is reasonable based upon my training and experience as a range instructor as well as through applied human factors psychology,” Blake said in the 51-page report released this week.

Employees at a local Taco Bell drive-thru had called cops the day of the incident to report a man slumped over at the wheel of his Mercedes.

Responding officers said they found McCoy unresponsive with a handgun in his lap and the car’s transmission in drive.

Body camera footage released in March shows McCoy beginning to move inside the car, scratching his shoulder before bending forward and reaching down toward the floor, the San Francisco Chronicle reported.

Officers shout at McCoy to show his hands and almost immediately open fire through the windows, killing him in a barrage of bullets, the video shows.

Blake’s report found that officers fired on McCoy three seconds after first ordering him to show his hands. According to Blake, the cops had probable cause to believe McCoy posed a threat.

“Officers are not required to wait until a weapon is pointed at them to take the necessary steps to save their own lives,” Blake wrote.

Attorney John Burris, who represents McCoy’s family in a wrongful death lawsuit against the city, told the paper on Wednesday that the report’s findings didn’t surprise him.

The family has called McCoy’s death an “execution by firing squad.”

City Attorney Claudia Quintana said the report was recently shared with Vallejo police officials and will be presented to the city council Friday.

It will not be used as part of the Solano County District Attorney’s Investigation, which will determine whether the officers are charged, Quintana said.