1971 Mercedes-Benz AMG 300SEL 6.3 Race Car (W109) "The Red Pig"

By taking the powerful 6.3 litre V8 Mercedes-Benz M100 engine from the luxurious 600 limousine, 
and fit it into the regular Mercedes-Benz W109 S-Class model 
which only had 6-cylinder engines at that time. 
The result was a nearly 2-tonne saloon with performance similar to most dedicated sports cars of the era. 
AMG, now the sports tuning subsidiary of Mercedes-Benz, 
but then a small local tuning company founded by former Mercedes engineers, 
produced special versions of the 6.3 to compete in racing events, 
usually with the engine further enlarged to 6.8 liters or more. So-called "Red Pig". 
It finished 2nd in the 24 Hours of Spa in 1971.
Five were made, three racers and two test cars. 
The automaker claimed 0-62 mph (0–100 km/h) time of 6.3 seconds 
as the fastest production sedan with top speed of 229 km/h. (wikipedia)

 

  

 (Photos from mercedes4arab.com & autowp.ru)