The digital activity, created by Saatchi & Saatchi Los Angeles, takes its cue from TV shows such as MTV's 'Punk'd', in which celebrities are set up as the victims of elaborate practical jokes.
The Toyota Matrix campaign enabled people to nominate a friend as the subject of a fictitious scam involving characters played by actors.
The push was promoted with an online video, in which viewers were encouraged to share some information about their chosen victim.
It said: "Pick one of our maniacs to mess with their heads for five straight days while you sit back and watch it all go down."
However, the campaign has led to one victim, Amber Duick, filing a lawsuit against Toyota, after she received a series of emails from beer swilling, English football fan Sebastian Bowler, who said he was planning on staying with Duick.
Bowler's emails to Duick indicated he knew her, where she lived and that he was on his way with his pit bull, Trigger, to hide from the police.
In his second email, Bowler listed his MySpace page. One of the nine emails to Duick, the suit alleges, was a bill for $78.92 from a motel for Mr Bowler's one-night stay there, plus damage to a TV set and picture frame.
Nicholas Tepper, Bowler's Los Angeles attorney, said: "My client was terrified.
"She slept with a machete next to her bed and she slept with mace. She could barely sleep or eat normally."
The suit states that Duick "became physically ill" because she was convinced "a disturbed and aggressive" stranger was en route to her house.
The final email in the campaign reveals to Duick that she has been "punk'd" and all the emails were part of an ad campaign for the Toyota Matrix, the suit claims.