What's the Most Expensive Single Car Modification Ever Done?

A diamond-encrusted Mercedes-Benz SL600, unveiled at the 2007 Dubai Auto Show, is the most expensive single car modification on record — covered in roughly 300,000 individual diamonds, with the diamond work alone estimated at around $3.5 million and the car's total value placed near $4.8 million. It wasn't a concept or a static display piece either: underneath the diamonds sat a fully functional V8 (with a V12 version also produced), capable of 0-60 mph in 4.4 seconds.

In plain English: someone took an already six-figure luxury car and added several million dollars' worth of literal diamonds to the outside of it, and then actually drove it.

The Car That Set the Benchmark

The diamond SL600 exists in two known versions — one in white, one in gold — and both belonged to Saudi Prince Alwaleed bin Talal's private collection of roughly 50 cars. Every visible surface was affected: diamond-studded badging, diamond-covered exhaust tips, and a diamond inlay across the paintwork itself. The practical consequences of owning something like this are almost as remarkable as the build itself — a single touch is reported to cost around $1,000 to have professionally cleaned and re-set, and even a minor scratch runs into thousands of dollars to repair. It's a car that's genuinely more expensive to maintain than most people's houses are to insure.

The Rest of the Field

The diamond Mercedes isn't an isolated case — it sits at the top of a genuinely competitive, if niche, category of ultra-wealthy car customization. A diamond-studded Maybach 62S Saloon was unveiled at the de Grisogono Party during the 2011 Cannes Film Festival, one of the most exclusive events on the luxury calendar, though covered only partially in stones rather than the SL600's full treatment. In 2016, a wealthy Saudi tourist arrived in London with an entire fleet of bling-covered supercars, including a gold-plated Mercedes G63 AMG 6x6 alongside gold-plated Rolls-Royce and Lamborghini examples — an entire convoy of seven-figure modifications rolling through central London at once. Separately, a Mercedes-Benz SLR McLaren nicknamed the "Red Gold Dream" combined 24-carat gold plating with rubies across its trim, and was fitted with a GPS tracker specifically because the owner was, understandably, worried about theft.

The One That Doesn't Quite Count

You'll frequently see a "$7.5 million solid gold Lamborghini Aventador" cited as the most expensive car modification ever attempted — and it's worth being precise about what that actually is. Reporting on the project describes a 1,100-pound block of solid gold intended to be carved into an Aventador-shaped model, weighing around 55 lbs once finished, with the stated goal of setting Guinness records for most expensive model car rather than most expensive modified drivable car. Whether it was ever fully completed and delivered as a genuinely road-going vehicle is unclear from available reporting — which is exactly why it doesn't take the top spot here. The diamond Mercedes SL600, by contrast, is a documented, functioning, driven car.

Why Anyone Actually Does This

At the extreme end of car culture, these builds aren't really about performance or even primarily about looking good by conventional standards — they're a direct, physical display of wealth, in the same tradition as gold jewellery or a superyacht, just applied to a car instead. It's a genuinely different motivation from the rest of modification culture, where the money spent on a build is usually chasing a lap time, a specific look, or a personal connection to the car. A diamond-covered SL600 isn't trying to be faster or handle better — the diamonds are the entire point, and the car underneath is just the canvas they're applied to.

For modifications rooted a little closer to actual performance and driving feel, browse the advice and tips section for builds that spend the money where you can actually feel it.