Salon Privé has relocated from London to Blenheim Palace for its 10th anniversary, and the three-day event culminates with a "public day" on Saturday.
Co-founder David Bagley described the cars on display as "amazing".
They include the Aston Martin DB10, only 10 of which were made, soon to be seen in James Bond movie Spectre.
However, 007's car can only be seen by premium ticket holders.
Mr Bagley said: "It's the first time we've had a public day.
"For me it's a real opportunity for dads and their lads. All kids love cars.
"The cars we bring here, half of them will have never been seen before. There's going to be a lot of noise, a lot of atmosphere."
There are supercar and hypercar models on show by Ferrari, Koenigsegg, Pagani, McLaren, Zenvo, some of which are worth in excess of £1.5m.
The top tier hypercar category is one increasingly used by car aficionados, and refers to the most expensive and highest-performing supercars.
The event is usually targeted at private buyers, collectors and enthusiasts, but "outgrew" its original locations in Hurlingham and Syon Park.
Mr Bagley added: "As beautiful as they were, Blenheim now offers us an opportunity to create a lovely private event on the south lawn and a public event on the Great Court."
The public part of the show will include a grand parade of more than 60 supercars from 1975 to the present day.
Jamie Spencer-Churchill, the 12th Duke of Marlborough, said it was an honour for the palace to be involved.
"My wife, and son The Marquess of Blandford, and I are personally looking forward to the event as big motor enthusiasts," he added.

The specialist system monitors the strain from wind, traffic and the weight of the bridge.
Specialists were brought in to install the monitors which will feed data back to the control room.
The bridge was closed to all traffic on 4 December after a crack was discovered in a truss under the carriageway.
Engineers hope to have it repaired and open to traffic again by 4 January.
An inquiry will begin after that, with MSPs agreeing that the "immediate" priority should be to get the bridge reopened.
The lorries were sent over the bridge in different patterns over five hours of tests on Saturday.
An inquiry will focus primarily on the structural defect, and an independent technical adviser will be asked to take part.
The inquiry aims to call officials from bridge operator Amey, its predecessor the Forth Estuary Transport Authority, Transport Scotland staff and Transport Secretary Derek Mackay.
A prestigious motor show for rare and luxury cars is to open to the general public for the first time.
[NEXT_CONCEPT]
Ten lorries have been used during tests of a new state-of-the-art structural monitoring system installed at the Forth Road Bridge for the first time.