James Durrigan, from Ardee, Co Louth, pleaded guilty on his own behalf and as director of his company James Durrigan Motors of Ardee, to two counts of entering into an agreement to distort or directly or indirectly fix the price of Citroen cars between June 1997 and February 2002.
The court heard Ireland's Competition Authority began an investigation in 2003 into the Citroen Dealers' Association (CDA), in which Durrigan was involved.
It discovered minutes of meetings which revealed Durrigan and other members met in hotels to discuss issues including price-fixing.
The authority also discovered a pocket-sized laminated card which was devised by the CDA and given to member dealerships.
The card showed the maximum discounts which sales executives were allowed to give customers for cash deals.
Prices were also fixed from time to time on used cars.
Durrigan was given a three-month suspended sentence, while his company was fined 12,000 Euros at Dundalk Circuit Court.