The department has been far busier than McLaren executives originally anticipated. When planning for McLaren's early MP4 12C model a few years back, the company estimated it would see about 10 percent of the cars undergo special treatment.
In reality, the figure was around 26 percent, with buyers mostly asking to modify the color and trim.
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Though virtually every P1 undergoes customization, the service is not as prevalent among its lower-priced 650S models, of which about 15 percent have so far been customized.
The high profit margin for custom works is something that carmakers covet. Virtually all high-end carmakers now offer their own version of McLaren's Special Operations unit.
Daimler, for example, expects the majority of its Mercedes-Maybach S600 Pullman stretch limos will get some level of customization. If that includes heavy armoring, the total price tag could readily top $1 million.
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Bentley and Rolls-Royce boast they'll even match a car's leather or paint to a customer's favorite color, even if that means matching a shade of lipstick.
"If you get the quality right and relationship with the customer right, the price almost doesn't matter," Mackenzie said.