A Long Island man’s $70,000 dream car turned into a nightmare when the luxury ride’s self-closing door chopped off his right thumb.

Now victim Godwin Boateng sometimes wears a fake digit from a $3 magician’s kit in its place — and is suing car manufacturer BMW.

“I carried my thumb into the hospital, and they said, ‘What happened to you?’ ” said Boateng, 61, a software engineer from Valley Stream.

“I said, ‘My car door.’ I’m holding my thumb, they took it and put it on ice. The nurse said, ‘Maybe the doctor can put it back on.’ The doctor came in and looked at it and said, ‘I’m sorry.’ He said he couldn’t. The way it got severed, it couldn’t be saved.’’

Boateng’s lawyer, Avi Cohen, called the BMW X5’s door nothing short of “a guillotine.”

“There’s something wrong with the design,” he said.

Boateng was meeting a friend for dinner on July 6, 2016, and had been standing outside the black SUV when he rested his right hand on the driver’s door column, according to his Brooklyn federal suit.

“With the front driver’s door approximately one-foot ajar, the SCAD [Soft Closing Automatic Doors] sensor activated the electric motor, which pulled the driver’s door firmly, and not ‘so softly’ snapped through the flesh, nerves, blood vessels, tendons, musculature and bone structure of Boateng’s right thumb,” his suit says.

Boateng said that even after two surgeries, his hand remains swollen. While part of his right thumbnail has grown back, he sometimes wears the fake finger because the tip is still sore and sensitive.

“Sometimes it feels like someone is putting knives in there. It’s painful beyond belief,” he said.

Boateng, who is right-handed, said he has trouble doing basic tasks like fastening buttons, tying his shoes and typing.

The disfigurement has also affected his work, as he’s often now too embarrassed to give presentations, he said.

He is suing for unspecified damages.

“I don’t know how you put a price on it; it’s a life-changer,” Boateng said.

His suit says BMW knew that SCAD had faulty sensors yet did nothing to correct it or warn customers.

“There has to be some sort of mechanism to protect you from that outcome,” Cohen said.

Boateng said he had been so excited to get the car, and “I thought [SCAD] was a really cool feature.

“It never crossed my mind it would do so much damage,” he said.

A lawyer for BMW declined to comment, citing pending litigation.