I've been sworn to secrecy since for months, but now I can tell all.
At the New York auto show last March, Mercedes ushered a small number of journalists across the road to a photographic studio.
Once relieved of our cameras and mobile phones, we were led into a small room where two cars lay hidden under covers.
The first was a special-edition SL with a marketing connection with an expensive watch. The details were wiped from my memory after the second car was unveiled.
Having seen the V12, twin-turbo, SL65 AMG Black Series in the carbon, I can only say that you are in for a treat. It looks utterly fantastic, emitting intent like virtually no other car I've ever seen.
Although it's clearly an SL, every panel has been heavily restyled and then effectively draped over what looks like a Le Mans-ready chassis. The massively wider track and incredibly wide rear wheels just scream hyper-car.
But there's another interesting aspect to the SL Black Series. It's likely to mark a new peak in accessible performance.
For years, supercars were hard to drive, uncomfortable and tricky to handle, which naturally restricted the potential customer base.
It was the arrival of cars like the Bentley Continental GT and Ferrari 550M (and the upcoming Ferrari California) that made supercar performance accessible. The upshot was soaring sales.
This SL, despite extensive modifications, is still based on a rapid and comfortable GT car. It even gets a five-speed autobox.
I reckon it's another first for Mercedes: the hyper-car made easy. Never before will 661bhp and 738lb ft have been unleashed in such a useable way.