Dashcam footage has emerged of a black Porsche, believed to be the same vehicle involved in the horror crash that killed four police officers, speeding down the Eastern Freeway last month.

Uber driver James Tsagros was travelling close to 100km/h on March 21, about 5.10pm, inbound on the Eastern Freeway towards the Hoddle Street exit when a black Porsche sped past.

"All of a sudden this car has gone swoosh past me on the left hand side, my car just vibrated. It was like a Formula 1 car went by," Mr Tsagros told The Age.

"I've been driving for 35 years and I've never experienced anything like that on the road."