This one-off $4m Ferrari was built in secret and is the rarest Ferrari model ever produced

This is the rarest Ferrari ever built.

In fact, the word ‘rare’ doesn’t cut it, because there’s only one of these in the world.

And no one even knew it was being built until it was unveiled.

READ MORE: Ferrari’s new halo hypercar spotted in Italy with massive rear wing

The Ferrari P4/5 by Pininfarina is the rarest, most unique street-legal Ferrari in the world.

It’s owned by Jim Glickenhaus, a collector and race team owner, who oversaw the entire manufacturing process.

While most collectors buy these cars and never use them, Glickenhaus loves this car so much he actually drives it on a regular basis.

Not that long ago, the P4/5 was the protagonist of a YouTube video in which it was being detailed.

Imagine that.

It may not be immediately clear just by looking at it, but the P4/5 is based on a Ferrari F430.

The engine is a 6.0-liter V12, sending over 660 horsepower to the rear wheels via a six-speed manual gearbox.

Thanks to its lightweight construction and its low drag coefficient, the P4/5 can reach 60 mph (97 km/h) from standstill in around 3 seconds.

The top speed is 233 mph (375 km/h).

Even though it’s based on a F430, the P4/5 incorporates design cues from other iconic Ferraris.

The rear window, for example, draws its inspiration from the 512S, while the side vents are similar to those found on the Ferrari 330 P3.

The ‘normal’ doors are gone, too, and the car now has butterfly doors.

The car was unveiled at Pebble Beach in 2006, and it reportedly cost Glickenhaus around $4 million.

At today’s rate, when adjusted for inflation, that’s over $6 million.

However, the true value of the car is probably higher than that – for two reasons.

Because there’s only one in existence and, more importantly, because Glickenhaus isn’t thinking about selling it.

DISCOVER SBX CARS: The global premium car auction platform powered by Supercar Blondie