A rare two-digit numberplate has fetched a record-breaking $745,000 at auction in Sydney overnight.

The historic black and white New South Wales plate features the number '29' and smashed the previous record for the most expensive numberplate sold at auction by $56,000.

That record belonged to the NSW plate '2' which sold for $689,000 in 2003. The previous record for a two-digit plate was the Victorian '21' which sold for $530,000 at auction in 2016.

The history of '29' dates back to 1915 when it was registered to Mr MacCormick of Macquarie Street, Sydney. He had the plate on his Minerva.

The numberplate was sold overnight at the Shannons Autumn Classic Auction. The most expensive car sold was $180,000 for a restored 1970 Ford XY Falcon GT.