For many years, consumers worldwide have had access to a variety of diesel vehicles, from large-scale productions to small runs. BMW is no exception. 

M21

In the early ’80s BMW saw competitor Mercedes producing diesels that put out between 59hp and 85hp. These weren’t the type of numbers BMW would be happy with and they sought to do better. Modifying mainly only the grade of iron used in the existing M20 straight 6 engine, their M21 diesel engine was born. Opting for an indirect injection, rather than the direct injection used in vehicles today, they used a “swirl chamber” injection where the fuel is sprayed into a chamber above the combustion chamber. This also resulted in a quieter engine sound. Paired with a Garrett T3 turbocharger the BMW’s 1983 524td produced 115hp and 112–162 lb⋅ft torque, performing much better than the Mercedes counterparts. The M21 engine ended production in 1991, but not before appearing unexpectedly in Ford’s Lincoln Mark VII & the Vixen RV.

Vehicles using the M21 engine: The BMW 524td

M57

Introduced in Europe in 1998, the M57 was a totally new design for BMW. It was a watercooled, inline six with common rail injection. It was made with a dual overhead camshaft and also opted for aluminum over cast iron in crankcase construction. The power output saw an increase from its European predecessors ranging from 161 – 282 horsepower and 258 – 428 lb⋅ft of torque. The engine featured a variable turbine geometry (VTG) turbo. VTG turbos narrow the passageways at low speeds to increase air velocity and reduce turbo lag by improving low-end torque. Whereas at high speeds, the passageways are opened to allow more flow and maintain efficiency and power. In 2008 BMW brought the M57 engine to the US market with the 335d and X5 xDrive35d. The M57 engine was known for its reliability. Later versions were fitted with diesel particulate filters (DPF) to accommodate emissions standards for various regions

Vehicles using the M57 engine:

• BMW 335d (E90) 2009–2011 
• BMW X5 xDrive35d (E70) 2009–2013 

N57

The N57, which was first developed in 2008 was the successor to the M57. It was designed to be more efficient and powerful than the M57. As with previous engines the new version saw an increase in power as opposed to its predecessor. The newer N57 produced between 201–375 hp and 332–546 lb⋅ft. Like the M57 it featured a VTG turbo. The N57 was also the first engine to come with a DPF from the factory on all versions. The engine also moved the timing chain to the rear of the engine. Although it would call for a costlier repair vs the M57 it was generally considered to be more durable than its predecessor

Vehicles using the N57 engine:

• BMW X5 xDrive35d – 2014-2018
• BMW 535d – 2014-2016
• BMW 740Ld xDrive (F01 LCI) – 2015

N47

The N47 engine which was an inline-four produced from 2007 to 2017. The engine produced between 94-215hp and 173–332 lb⋅ft of torque. The engine had a much more limited run in the US than other engines. Its successor the B57 was not introduced into the US market

Vehicles using the N47 engine:

• BMW X3d – 2015-2017
• BMW 328d  – 2014-2018