A 30-year-old man was killed on his way to his sister's wedding after his car spun out of control and smashed through two signposts on the M5.

Ziyaad Barnes died near the Klipfontein slipway on Saturday night. He drove ahead of the rest of his family on their way to Kirstenbosch for the wedding reception.

After the crash, a passing motorist stopped at the scene and got out of his car.

Barnes, still conscious, reportedly told the man that he was "okay", before dying mid-sentence. The wedding party stopped at the wreckage a few minutes later. His mother wanted to see him, but relatives held her back.

"The car had been so badly mangled, it took paramedics more than three hours to remove the body," said ER24's Tristan Wadeley.

At his funeral on Sunday, friends and family packed his parents' Rondebosch home.

"Everyone was saying how they'd just seen him last week or spoken to him the night before, like he was still alive and well," said Zane Rinquest, Barnes's best friend.

"We expected him to walk through any moment with his catchphrase, 'rolling like tycoons', but it didn't happen. Even after burying him, it still hasn't fully sunk in."

Rinquest described his death as "the world's loss of a special and unique guy".

"He had a real zest for life. He was the type of guy you'd want as a best friend minutes after meeting him. His death has been hard for everyone to accept, especially for his mother and his fiancée," said Rinquest.

He said Barnes was planning to get married in March.