Large traded as Select Motor Services and Trade Car in Moorwell Road, Scunthorpe.
A two-year investigation by Trading Standards officers was prompted by a complaint by a consumer, who found his car had a mileage anomaly.
Investigators subsequently discovered that Large bought cars with high mileage from various motor auctions, and re-sold them on auction sites and from his forecourt with the mileometers showing low mileage.
Some also had a false service history and MoT certificates showing lower mileages.
After admitting the offences, Large was sentenced this week at Sheffield Crown Court to 12 months imprisonment on each of 25 counts of clocking, to run concurrently.
The court heard Large made around £28,200 profit on the 25 vehicles, but after repairs and MoTs, his actual profit was more like £16,000.