The car will go on limited display at the auction house's New Bond Street store on Thursday and Friday.
A rare vintage sports car originally owned by Hari Singh, the last Maharaja of Kashmir, will be the highlight of an auction in London in December.
The 1924 Vauxhall 30-98 OE Velox Tourer, recognised among the finest British sports cars of the vintage era, is estimated to fetch between 330,000 pounds and 390,000 pounds when it comes up in the Bonhams Bond Street Sale on December 2.
The car will go on limited display at the auction house's New Bond Street store on Thursday and Friday this week.
"This is the finest 30-98 ever offered by Bonhams, and its rare aluminium body and extraordinary specification makes it one of the most important examples in existence," said Sholto Gilbertson, Department Director at Bonhams.
"Its fascinating history only adds to the significance of this motor car, and we look forward to offering it at our Bond Street Sale," he said.
According to experts, the car is an "incredibly special example of its kind as the Maharaja – known as a particular and exacting ruler – wanted it to be as symmetrical as possible."
He ordered an extra handbrake on the passenger's side, a door on the passenger's side (non-standard) and a split windscreen, though he drew the line at two steering wheels.
The car passed through several important owners in India, Pakistan, the US and the UK, including the legendary car collector and master watchmaker George Daniels and Ed Roy, an influential Bostonian in the motoring world and president of the Vintage Sports-Car Club of America.
Hari Singh, one of the most important figures of Kashmiri history, acceded to the throne of Jammu and Kashmir in 1925 and made quick changes to laws that he considered outdated and cruel.
He made primary education compulsory, outlawed child marriage and allowed all lower castes access to places of worship.
Bonhams, founded in 1793, is one of the world's largest and most renowned auctioneers, offering fine art and antiques, motor cars and jewellery. The main salerooms are in London, New York, Los Angeles and Hong Kong, with auctions also held in Knightsbridge, Edinburgh, Paris, San Francisco and Sydney.