[Upated]: Our predictions about the final sale price of Jenson Button's Porsche were a little too conservative as it has sold for £317,464, which is $439,099 at the current exchange rates. A total of 99 bids were submitted for the rare 911.

A one-off example of the mighty Porsche 911 Turbo (964-generation) is up for grabs, and there are several reasons why it is worth your attention. With six days left until the end of the auction and after 57 bids, it’s currently at £200,000 or about $274,000 at the current exchange rates. We’ll get to the bidding details in a minute, but let’s talk a little about why it is so special.

Built in March 1994, this particular 911 was originally commissioned by the Sultan of Brunei, and that fact alone means it’s a rare and unique specification. According to the ad’s description, it’s one of only a few 964s assembled with the X88 power package and a standard front end. More importantly, it’s the only example finished in Horizon Blue Metallic, and pretty much this means it’s a one-off car.

Gallery: 1994 Porsche 911 Turbo 3.6 for sale

Adding further to the exclusivity of this 911 Turbo is the fact that it is still owned by the 2009 Formula One World Champion, Jenson Button. Imported to the United Kingdom in 2009, the sports car has an active MOT (UK’s annual test of vehicle condition and roadworthiness) with zero advisories. The odometer shows 18,592 original miles and judging by the photos, it's in factory condition inside and out.

Under the hood is a 3.6-liter turbocharged flat-six producing 380 horsepower (283 kilowatts) mated to a five-speed manual gearbox and a limited-slip differential. Of course, the car features a rear-wheel-drive layout and rides on original Porsche 18-inch wheels. No known electrical or mechanical faults are reported, and no warning lights are showing on the dashboard.

The last bid was registered about 20 hours ago (at the time of writing this article) and judging by the bidding history (available at the source link below), there are two or three serious potential buyers who are bidding regularly. If you want to join the party, prepare to spend at least $300,000 given how intense the bidding has been in the last few days.

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