The R35-generation Nissan GT-R may be the fastest iteration of the famed Skyline family, but it is far from the most exclusive.

In fact, one has to look back to the 1990s to find the rarest Skylines ever built, few of which are as special as the Skyline R32 HKS Zero-R.

The Skyline R32 HKS Zero-R showed up in the early 1990’s when HKS was building bespoke high-performance road cars, much like RUF does with Porsches in Germany.

The tuning company initially built four examples, but in order to meet homologation, was required to crash test a number of cars to register them as one-off models. HKS calculated that crash testing would cost roughly $116,400 for each Zero-R built and decided to abandon the project.

Of the four units built, HKS kept three of them in Japan while the Sultan of Brunei purchased the fourth. He no longer owns the vehicle, but it still resides in Brunei and was recently present at a small car gathering.

The current owner has equipped the vehicle with a RB26 engine, which powered the R34 generation. In its current guise, the turbocharged straight-six pumps out 600 hp. Key styling differences between the HKS Zero-R and all other R32 Skylines is the custom rear fascia that includes dual tailpipes and an intriguing bumper/diffuser design. The car also ditches its rear seats and instead, features a large fuel cell in the rear.

In 2005, lax legal procedures in Japan allowed HKS to build another handful of Zero-Rs, registering them as modified Skyline R32 GT-Rs, though the original four remained the most sought after.