Too many people use "unique" to mean merely special when the word really should describe something that's one-of-a-kind. This E28 BMW M535i is truly a unique machine after the owner's 16 years of work to personalise it.

Colin Baker bought this old 5 Series with the intention of doing a sympathetic restoration of it. Clearly, that didn't happen. Instead, Baker painted the saloon purple and loaded the vehicle with 24-karat gold-plated trim.

The Amethyst metallic colour is a BMW Motorrad shade from the 1980s. Baker is a professional car painter and uses a custom mix of the shade to add some extra ultraviolet hues to it. Another interesting touch is that pocket watches are on the caps for the oil, charger cooler reservoir, and fuel tank.

Baker started by just gold-plating the turbo, but then he got addicted to adding more. Now, most of the interior and exterior trim have the previous-metal covering. Baker estimates there is £5,500 to £6,000 of gold on the car. The next plan is to coat the roll cage in the shiny material.

The current turbocharged powertrain makes around 500 bhp (373 kilowatts). Baker plans to install a second turbo next, and it would have gold plating, too. There are nitrous tanks in the boot, but they aren't currently operational. 

The 5 Series rides on an air suspension. It was apparently quite a job to install because the company didn't make a kit specifically for the E28.

Inside, there are more purple and gold touches. Much of the cabin has Alcantara upholstery. Baker stitched all of these pieces by hand.

Baker has no plans to sell his M535i. After so much work into the extensive modifications, the only path he sees forward is to continue personalising the saloon for years to come and then pass it down to family.