The M115 engine family was a straight-4

Straight-4

The inline-four engine or straight-four engine is an internal combustion engine with all four cylinders mounted in a straight line, or plane along the crankcase. The single bank of cylinders may be oriented in either a vertical or an inclined plane with all the pistons driving a common crankshaft....

 automobile engine from Mercedes-Benz

Mercedes-Benz

Mercedes-Benz is a German manufacturer of automobiles, buses, coaches, and trucks. Mercedes-Benz is a division of its parent company, Daimler AG...

 in the 1970s. The same engine was produced in several versions with differing volume, compression, and horse power according to its application.

M115.920

The M115.920 is a 2.2 L engine with a power output 103-105 hp

Applications:

• 1968-1973 220 (W115.010)

M115.923

The M115.923 is a 2.0 L (1988 cc) 95 hp (70 kW) engine.

Applications:

• 1968-1976 200
  Mercedes-Benz W123
  W123 is the internal chassis-designation Mercedes-Benz used for their executive line of cars, manufactured between 1976 and 1985.The W123 models surpassed their predecessor, the W114 and W115 models, as the most successful Mercedes, selling 2.7 million cars before replacement by the W124 after 1985...
  
   (W115.015)

M115.924

The M115.924 is a 90-120 hp engine, depending on compression. The 90 hp is 2200 cc (66 kW).

Applications:

• 1968-1973 220 (W115 coupé)

M115.926

The M115.926 is a 86-95 hp (63kw-70kw) engine, depending on compression.

Applications:

• 1968-1977 220

M115.938

The M115.938 is a 2.0 L (1988 cc) engine with an 87 mm bore and 83.6 mm stroke. Power output was 94 hp (70 kW).

Applications:

• 1975-1980 200
  Mercedes-Benz W123
  W123 is the internal chassis-designation Mercedes-Benz used for their executive line of cars, manufactured between 1976 and 1985.The W123 models surpassed their predecessor, the W114 and W115 models, as the most successful Mercedes, selling 2.7 million cars before replacement by the W124 after 1985...
  
  

M115.939

The M115.939 is a 84-94 hp engine, depending on compression.

Applications:

• 1976-1980 200
  Mercedes-Benz W123
  W123 is the internal chassis-designation Mercedes-Benz used for their executive line of cars, manufactured between 1976 and 1985.The W123 models surpassed their predecessor, the W114 and W115 models, as the most successful Mercedes, selling 2.7 million cars before replacement by the W124 after 1985...
  
  

M115.951

The M115.951 is a 110 hp engine.

Applications:

• 1973-1979 200 (W115.017)

M115.952

The M115.952 is a 2.3 L (2277 cc) engine with 89 hp.

Applications:

• 409 LF Transporter
  Mercedes-Benz T2
  The Mercedes-Benz T2 is a transporter built by Daimler-Benz. The T2 is also known as the "Düsseldorf transporter", since it was built until 1996 in Düsseldorf. The third series, built from 1996 at Ludwigsfelde, is branded the Vario. Some units of the T2 are assembled by Daimler-Benz Espana S.A. in...
  
  

M115.954

The M115.954 is a 2.3 L (2307 cc) version with a 93.8 mm bore and the same 83.6 mm stroke. Power output was 109 hp (81 kW).

Applications:

• 1976-1981 230
  Mercedes-Benz W123
  W123 is the internal chassis-designation Mercedes-Benz used for their executive line of cars, manufactured between 1976 and 1985.The W123 models surpassed their predecessor, the W114 and W115 models, as the most successful Mercedes, selling 2.7 million cars before replacement by the W124 after 1985...
  
  
• 1976-1981 230C
  Mercedes-Benz W123
  W123 is the internal chassis-designation Mercedes-Benz used for their executive line of cars, manufactured between 1976 and 1985.The W123 models surpassed their predecessor, the W114 and W115 models, as the most successful Mercedes, selling 2.7 million cars before replacement by the W124 after 1985...
  
  
• 1976-1981 230T
  Mercedes-Benz W123
  W123 is the internal chassis-designation Mercedes-Benz used for their executive line of cars, manufactured between 1976 and 1985.The W123 models surpassed their predecessor, the W114 and W115 models, as the most successful Mercedes, selling 2.7 million cars before replacement by the W124 after 1985...