Neil Addison, 55, carried out the attacks on young women in the Fife area over a period of more than three years.
Several of his victims described how Addison, of Cupar, had initially been friendly but started groping them a few weeks into their tuition. He was convicted of 14 charges at Dundee Sheriff Court and sentence was deferred.
Sheriff Tom Hughes ordered Addison be remanded in custody and placed him on the sex offenders register indefinitely.
He told Addison: “These young women were confined in a car with you at a time when they looked to you for assistance. For several weeks you ingratiated yourself to them then as time went on you took more and more liberties with them. Heaven knows what would have happened had this gone untraced.”
The court had heard the women attacked by Addison were all aged between 17 and 21.
His final victim, who was 17 at the time, told the jury he touched her “just above the knee” during early lessons. The victim, who is now 18, said he moved on to touching her upper thigh as time went on.
During their final two-hour session, she said he put his hand between her upper thighs, before thrusting his hand down her top and grabbing her left breast.
The teenager said: “I was driving with one hand and trying to push him away.
“At one point the side of his hand had been in my crotch. He was then pinging my waistband.
“When I got out of the car he said, ‘don’t tell anyone about this.’”
Addison, who carried out the attacks on the women between June 2014 and August 2017, was detained by police the following day.
During police questioning, he admitted he was “possibly” attracted to the girl and added: “Stupid, stupid - 18-year-old head on an older body.”
Addison, 55, of Holly Park, Cupar, Fife, denied a total of 15 charges on indictment, allegedly committed between June 2014 and August 2017 during car journeys across north east Fife.
One of the charges was withdrawn at the end of the Crown case after the court heard the alleged victim emigrated to Australia.
Sheriff Tom Hughes deferred sentence until September 10 for social work background reports.