A Surrey used car salesman sold vehicles with faulty mileage and worthless warranties to unsuspecting customers, a county court heard.
Witnesses told the Guildford court how Godstone Cars owner Mark Phillimore failed to comply with terms of warranties and left customers with cars requiring expensive repairs.
Trading Standards led the civil proceedings against the businessman, who denies charges of breaching the Trade Descriptions Acts and Business Names Act.
The agency told the court it had more than 100 complaints against Phillimore and its dealings with him went back as far as 2004.
Phillimore used a range of trading names after attracting bad publicity including Broughton Group, Godstone Cars and Prestige and Performance.
Prosecuting barrister Jerome Wilcox said: "The complaints continue. He's the sixth most complained-about business in the whole of Surrey, out of approximately 60,000."