Police say it was lucky nobody was injured when a wheelie bin was thrown from an overpass and onto a car in Melbourne's outer south-east.

The bin was thrown from a bridge on the Pakenham bypass, near McGregor Road, just after 4:00am on Friday.

The bin hit the driver's side of a vehicle and shattered the windscreen.

"An act of stupidity has caused extensive damage to a vehicle and left the driver shaken but luckily unhurt," Victoria Police spokeswoman Belinda Batty said in a statement.

Police said a semi-trailer, fully laden with LPG, had to take evasive action on the same road about 20 minutes earlier, to avoid being struck by a bin.

Police released images of the bin and the damaged car in the hope someone may have seen something.

Anyone with information is urged to contact Crime Stoppers on 1800333000.