Given the right level of status—and the bank balance to back it up—almost anything is possible in the world of collector cars.

Behind doors which even the most astute of collectors may struggle to unlock, cars considered too wild for mainstream manufacture are created; bespoke projects straight from the imagination are brought to life.

Perhaps one of the greatest examples of a collector’s vision made reality is this striking and rare Pininfarina-made drop-top, representing the peak of 1980s excess.

It is understood that towards the end of the decade, Italian coachbuilder Pininfarina was approached to undertake a custom project.

The coachbuilder was commissioned to create a supercar unlike any other.

It is thought that Pininfarina made seven almost identical but ultimately unique "Spider" adaptations of the bespoke order for Brunei Royalty, each finished in a different exterior and interior colour combination.

In addition to these Brunei cars, a very small number of Testarossa Spi...