Ryan Alexander Woodworth, aged 17, pleaded not guilty to three counts of taking a vehicle without consent.
The other teenager, who is 15 and therefore too young to be named, pleaded guilty to the same three charges.
Prosecuting advocate Roger Kane told the court that a Mercedes E320, a MCC Smart car, and a Volkswagen Polo were all taken without consent from the industrial estate in Ballasalla on June 16.
The two teenagers are accused of taking turns to drive the vehicles in the area behind the estate.
They were arrested and during an interview, Mr Woodworth, who lives at Saddle Road and was represented in court by advocate Paul Glover, said: ‘That ain’t me mate,’ but answered ‘no comment’ to all other questions.
The juvenile, who was represented by Louise Cooil, also answered ‘no comment’ during his interview.
Magistrates adjourned Mr Woodworth’s case until January 2, when a pre-trial review will be held in summary court.
The 15-year-old will be sentenced in juvenile court on December 4.
Bail has been granted for both with a condition not to enter Balthane Industrial Estate.