Truro magistrates heard that Nigel Rees, of Carnwidden Livery, Longdowns, Penryn and Ian Lewis of West Trevarth Barn, Lanner, Redruth bought salvage vehicles from insurance companies to sell on, a local paper reports.
The court case was in relations to the sale of a Mitsubishi Pajero, which was bought by the new owner for £650 before realising it had serious defects.
The car was later scrapped on the discovery of defective hoses and severe chassis corrosion.
Rees and Lewis denied all responsibility but were found guilty of selling a dangerously unroadworthy car, contrary to the General Product Safety Regulations 2005.
The pair were also ordered to pay costs of £3,400, £400 compensation and a £200 victim surcharge.
