A 20-year-old Suffolk man was killed when his car was slammed by a woman who was later charged with drugged driving, authorities said yesterday.

And the family of victim Imran Rehman got the heartbreaking news from a bystander when a worried relative called Rehman’s cell phone after spotting the crash scene and noticing his car was gone.

Rehman of 10 Ginger Court in Centereach was turning his 1999 Honda left from Smiths Lane onto Route 25 about 8:50 p.m. Monday when he was broadsided by a eastbound 2007 Audi driven by Debra Pendzick, 37, of 157 Chichester Ave. in Center Moriches.

Rehman’s devastated sister Momina Butt, 25, said she and her husband Qasim were on their way home from Wal Mart about 9:20 p.m. when they saw the lights from the accident.

When they got home, Imran’s car was gone and they got worried.

“We had that feeling because we saw the lights and we didn’t know what was going on,” Butt said. “My husband called Imran’s phone and she answered. She told him that he had passed away. That’s how we found out.”

The family rushed to the scene just blocks from their home, but Rehman had already been taken to the hospital.

Another sister, Nida Sadiq, 30, tearfully remembered her younger brother.

“He was just going to get a can of soda from the deli. He was a gem of a kid. He was just amazing. He’s the only brother I had and he was mature and wise way beyond his years,” she said.

Rehman, a student at Suffolk County Community College who dreamed of a career as a forensic scientist, was rushed to Stony Brook University Medical Center, where he was later pronounced dead.

The wasted perp was arraigned yesterday in the Suffolk County Courthouse on charges of driving while ability impaired by drugs and aggravated unlicensed operation of a motor vehicle, authorities said.

She was also taken to Stony brook complaining about chest pains, but was released yesterday for arraignment this afternoon.