Back in 1997, Audi retired the C4 generation of the A6, after only four years of production, but not before releasing the hottest model of the series, the S6 Plus.

Made in the final two years of production, 952 units saw the light of day, including 855 Avants (estate) and 97 sedans. The limited production number made it a true automotive unicorn, especially in the four-door body style, but this wasn’t the only highlight.

In fact, you had to pop the hood in order to see the icing on the cake, the 4.2-liter DOHC V8, with 32 valves, which replaced the 2.2-liter five-pot powering the standard S6. The engine produced 322 HP (326 PS / 240 kW), 95 HP (96 PS / 71 kW) more than the smaller lump, for a 0-62 mph (0-100 km/h) of 5.6 seconds (5.7 seconds for the Avant).

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Other highlights included the upgraded six-speed manual transmission, re-tuned suspension and bigger brakes, joined by the leather and Alcantara upholstery, electrically adjustable front seats with memory, electric sunroof and integrated phone.

This 24-year old S6 Plus was apparently gifted to Spanish newspaper El Mundo, in return for advertising space, and was used by the former CEO, before being sold to the Marquees of Antella. In the possession of its new owner, the car was repainted in Nogaro Blue, the original color, and the engine was rebuilt.

You already know where this is going, so we’ll cut to the chase by telling you that RMSothebys estimates that it will fetch between €40,000 and €60,000 ($43,853-$65,779). It will be offered without reserve at an online auction that kicks off on June 3 at 1:00 p.m. CET (7:00 a.m. EST) in Essen, Germany.