The oldest production Bentley in the world will go under the hammer in August and is expected to fetch in excess of $1 million.

Known as ‘Chassis No. 3’, this specific 1921 Bentley 3 Litre was the first customer car to leave the Bentley factory.

The car – labelled “one of the most important Bentleys in existence” – will be auctioned by Gooding & Company at Pebble Beach in California.

The engine from ‘Bentley One’ (fitted to the chassis from ‘Bentley 5’) was destroyed in a fire in 1994, while the second oldest Bentley is part of the manufacturer’s corporate collection.

Chassis No. 3 is much more original than the second car however, with complete matching component numbers, original brass brightwork, aluminium body and fully disappearing top as specified by the first owner.

It is in full working order and has recently competed in a number of vintage rallies, proving the 80-year-old vehicle’s durability.

In its day, the Bentley 3 Litre produced around 52kW of power and had a top speed of 129km/h. Weighing in at 1800kg, the car was equipped with a four-speed manual transmission, and early models like Chassis No. 3 only had brakes on the rear wheels.

Between 1921 and 1929, a total of 1088 Bentley 3 Litre vehicles were produced.