On August 13 an extremely rare 1955 Mercedes-Benz 300SL Alloy Gullwing will be auctioned at RM Sotheby’s, as shown on a report from gtspirit.com. The gullwing is part of the “The Pinnacle Portfolio” offered through the auction house, and industry watchers expect it fetch at least $5.5 million. The auction is one of the events associated with the Monterey Car Week and is held together with the Pebble Beach Concours d’Elegance.

This particular Gullwing is different front other similar luxury vehicles due to its aluminum body. Mercedes-Benz produced only 29 of these aluminum-bodied 300 SLs, which is around two percent of the total production run of the iconic sports car. Aside from its aluminum body, the 1955 Mercedes-Benz 300SL Alloy Gullwing also has a modified 3.0-liter Sonderteile engine offering 215 HP of power, which is 15 HP higher than the standard model of the luxury vehicle. The speed of this particular model is faster compared to the standard Gullwing due to its lighter weight and added power. Its original color was white and it featured the sports suspension Rudge wheels.

Rene Wassermann was the first owner of this 1955 Mercedes-Benz 300SL Alloy Gullwing. He drove the luxury vehicle from the factory to his home in Basel, Switzerland. The Gullwing was later sold, and went through a number of owners in the US. It ultimately became the property of Senator Newell Wood of Pennsylvania.

Before Hans Thulin had it restored by Kienle Automobiltechnik in Germany, it went through another set of owners. While undergoing restoration, some of the aluminum panels were either repaired or replaced. It was also given a Mercedes-Benz silver color. After it was restored, it became a part of the Pinnacle Portfolio as it joined a number of classic luxury sports cars.

The original color of this 1955 Mercedes-Benz 300SL Alloy Gullwing was white and had a leather interior, two-piece matching luggage, sports suspension and English instruments.