After seeing a £9,000 Audi A3 for sale on the Gumtree site, Shezan Shabir arranged a test drive in Dewsbury, but when he came back the next day he tricked the owner into looking at a mark on the roof and drove off in his car.
Bradford Crown Court heard today that the Audi had not been recovered and a week later Shabir tried to car-jack another car belonging to a University of Huddersfield student.
Prosecutor Oliver Thorne said Shabir went to Bradford to test drive the Volkswagen Scirocco, but after driving the vehicle aggressively he suddenly braked and stopped the car on the slip road to the M606.
Shabir, who worked as a takeaway delivery driver, told the student that he had to get out of the car because he had a knife and he was going to kill him.
Although no knife was produced, Shabir then opened the passenger door and pushed the car owner out of the vehicle onto the road.
Shabir locked the doors and tried to drive off but he was unable to move the car.
Mr Thorne said another vehicle then turned up and Shabir was driven away in it.
In a victim impact statement the student described how the incident in February had caused him considerable anxiety and led to him missing an exam a few days after the attempted robbery.
Shabir, of Old Mill View, Thornhill, Dewsbury, pleaded guilty to charges of theft and attempted robbery and the prosecution dropped a further allegation of robbery involving another car in Bradford after witnesses failed to attend court for a trial.
The court heard that Shabir was locked up for three years back in 2011 for another offence of attempted robbery involving an imitation firearm.
Barrister Tom Storey, for Shabir, said any money his client obtained by his offending was spent on "partying" with his then girlfriend and he now had nothing to show for his crimes.
Jailing Shabir for 40 months, the Recorder of Bradford Judge Jonathan Durham Hall QC referred to the fact that such offending was happening quite a lot nationally.
He said Shabir had worked out a plan to check on Gumtree to see who was offering attractive cars for sale and then committed offences under the pretence of buying them and going for a test drive.