The 6.9-liter V8 used in the Mercedes-Benz 450SEL 6.9 carried the engine code M100.
The engine began as the 6.3-liter M100 V8 fitted to the Mercedes-Benz 600 and the 300SEL 6.3. For the W116-based 450SEL 6.9, Mercedes enlarged it to 6,834 cc by increasing the bore. Despite its “6.9” badge, the actual displacement was therefore closer to 6.8 liters.
This enormous, hand-built V8 used Bosch K-Jetronic mechanical fuel injection and a dry-sump lubrication system. The dry sump helped preserve the sedan’s low hood line and held about 12 liters of oil. Output varied by market: European cars produced about 286 hp, while emissions equipment reduced power in North American versions.
The M100 made the 450SEL 6.9 a formidable luxury sedan. It could reach 100 km/h in roughly 7.4 seconds and had a claimed top speed of 225 km/h. Mercedes produced 7,380 examples from 1975 to 1980, making the model a rare descendant of the flagship 600.