The city added a thousand-dollar insult to an already painful injury when it demanded that a Brooklyn cyclist pay for damage to the police car that struck and sent him flying.

“I think it’s preposterous,” said Justin Johnsen, 31, who received the $1,263.01 bill from the city last month for the Nov. 5 accident on Flushing Avenue that left him with deep cuts that required stitches.

“I was upset. I was in kind of disbelief that they were going to send this letter after four months or so and ask me to pay damages for their vehicle, when they hit me when I was on a bicycle,” added Johnsen, who was not ticketed for the crash.

The case is at least the third in recent months in which the city has billed people for damages to police cars that hit people.

And after The Post made inquiries about Johnsen’s case, it became at least the third time the city abruptly dropped such a stunning demand for money.

“They should be sending an apology letter instead of a bill,” fumed lawyer Daniel Flanzig, who took the case pro bono after learning that the city was threatening to sue Johnsen if he didn’t cough up the cash.

As he usually does, the South Williamsburg resident was cycling to his design-engineer job in Red Hook at around 8:30 a.m. when the accident occurred.

“I had left the bike lane to make a left turn, and I looked behind me and saw that it was clear, and the farthest car was a fair distance,” he said.

Johnsen said he signaled to make the turn onto North Elliott Place from Flushing Avenue, but before taking the turn, he said, he “was swiped by this car on my left side.”

The 2009 Ford Taurus — which turned out to be an unmarked police car — knocked him from the bike.

“I didn’t feel too good . . . I got some big gashes to my elbows,” said Johnsen, who went to New York Methodist Hospital after the cops called for an ambulance.

Although the two cops in the car — including the driver, Sgt. Conrad DePinto, — were “pretty friendly” to him after the crash, they were “not apologetic at all,” Johnsen said.

He added that he hadn’t considered suing the police, even after racking up several hundred dollars in medical bills.