The 2007 Toyota Prius was located on Ballan-Daylesford Road at Ballan, west of Melbourne, between 3pm (AEDT) and 3.30pm on Monday.
Police are at the scene and are examining the vehicle.
His wife, Vicky, says there's still no evidence indicating what happened to her husband once he left Melbourne Airport.
"We really need the help of the public because we've just reached a dead end so to speak," Ms Rockefeller told ABC Radio on Monday.
"There's just nothing from 9.35 (pm). We've been through the phone records, credit cards, banks, tollways, everything. I mean, everything possible has been checked and there's just nothing."
Ms Rockefeller said she and her husband ran a multi-million dollar property investment business from their Malvern East home, investing in shopping centres and commercial property.
Mr Rockefeller's 52nd birthday is on Monday and his wife said he was in great spirits and there were no disputes, conflicts or hints of a secret life to arouse suspicion.
"When he's at home, we actually work from home, because I work for the business as well and we actually sit in the same office.
It's not a very big room, so I hear all the telephone conversations."
Mr Rockefeller was returning from a four-day business trip in NSW and rang his wife, who was attending the Australian Open tennis at 6pm on Thursday.
She had her phone on silent and missed the call, but sent him a text message and later received a message back, in which he was mainly talking excitedly about their daughter's university offers last week to study medicine.
"He also rang her at the same time to talk about that, I mean he was just over the moon about it."
When last seen, he was wearing a white shirt, pin-striped suit pants and was carrying a plastic shopping bag with about four grapefruit in it.
There is airport security footage of him driving his teal blue 2007 Toyota Prius out of the airport about 9.30pm.
"After that, absolutely nothing, he would normally have travelled home on CityLink, but they've checked that over and over again and he's not used that."
Ms Rockefeller said her family had absolutely no connection to the American Rockefeller dynasty, but she could not rule out kidnapping as a possible motive.
Detective Leading Senior Constable Peter Towner also said police could not rule out any possibility.
"There's no concrete leads or suspicion. For no apparent reason, he exited a plane, hopped in his car and hasn't been seen," he said.
"I'm just at a loss, I don't know why or what has happened."
Mr Rockefeller is about 180 centimetres tall, with dark wavy hair, receding hair line and a suntanned, olive complexion.
