Originally introduced in January 1976, the W123 was an instant success as the first year's production run was sold out shortly after launch. The insatiable demand meant owners who sold their car within the first year of production were able to get ask for the original sticker price.
A variety of different models were introduced over the years including the usual coupe and estate variants as well as a long-wheelbase sedan that was 24.8 inches longer than the standard model. The sedan, alone, was launched with nine different variants ranging from the 200 D to the 280 E.
Speaking of engines, there were plenty of options including a 2.5-liter six-cylinder petrol with 127 horsepower and a five-cylinder turbodiesel with 123 hp. Mercedes also explored a handful of alternative powertrains including a bi-fuel engine that could run on petrol or liquefied petroleum gas (LPG). Mercedes also developed an electric prototype and a hydrogen fuel-cell vehicle which was introduced in 1983.
Alternative drive systems weren't the only focus as improving passenger safety was another key objective. To this end, Mercedes created a more robust passenger cell and larger crumple zones. Engineers also thought about using airbags at an early stage and they became an option in 1982.
The W123 was phased out in the mid-1980s and by the time production ended Mercedes sold nearly 2.7 million models.