John Reid, 26, of Bartholomew Road, Morecambe, met the girl at a horse stable in the county, and quickly became obsessed with her, Preston Crown Court was told.
Between June and July 2016, Reid repeatedly sent messages and made phone calls to the teenager, changing numbers so that she could not block his calls.
After his victim reported him to police, he intentionally rammed a silver Peugeot into a car she was a passenger in on August 24, before making death threat calls to her.
The terrified girl had to install panic alarms and smoke alarms in her home.
In March this year, while he was on bail, Reid deliberately rammed his car at a Lancashire police officer, injuring him, as police tried to arrest him for a series of fuel thefts in Lancaster.
Imposing a 32 month jail term and a five year restraining order, Judge Robert Altham said: “ The circumstances of these offences are extremely troubling, both in separate ways
“It would seem you very rapidly developed a fixation of her.
“The complainant was out in a car with a friend, he was the driver. She became aware you were driving another car in the Broadway area of Morecambe. You followed closely behind her revving the engine, then made to overtake.
“In order to facilitate your overtaking the car had to pull over and as you came past you swerved into the driver’s door and drove off.
“The driver was understandably concerned - and then you returned to the scene. The complainant was frightened and calling for help
“She believed her life was under threat.
“You positioned yourself in front of the car and reversed quickly into that car, shunting it and spinning it round, causing it to go into the junction of Burlington Avenue.
“This was plainly an extremely dangerous and frightening incident - this is not a momentary rush of blood to the head in temper - this was the deliberate use of a motor vehicle on the highway to cause fear.
“After the incident the complainant got a call. You said this was her ‘worst nightmare, I’m going to kill you’. “
Whilst on bail, in March he committed a spree of other offending, stealing fuel from a service station on Caton Road and in Scotforth.
He deliberately drove at a police car when officer’s tried to arrest him.
An officer became crushed between a car and suffered hand injuries.
Reid admits harassment, dangerous driving, making off without payment and driving without insurance or a licence.
The judge said he had caused injury to a man who was “doing nothing more than his brave and courageous service”.
The court heard his intellectual abilities had been impaired since he plunged from a balcony in 2013 and ended up in a coma for nine months.
Defending, Tom Lord said: “ He wishes to apologise to his victim.
“Although his cognitive ability played a role in his decision making, he accepts he is to blame.”
He was banned from the road for 47 months and must do an extended retest