BMW Chassis Codes & Engine Codes

Every car manufacturer assigns an internal code designation to identify their vehicles. For BMW these are known as chassis codes and engine codes. These code systems help keep planning and development organized and avoids confusion. BMW engines are known by their M, N, B, S, P, or W codes while BMW chassis and bodies are known by their E, F, G, or U codes.
 

BMW Engine Codes

The engine codes used to be quite simple - M10 for four cylinder, M20 for small six cylinder, and M30 for the Big Six. But as the range of BMW engines expanded they needed a more meaningful code designation. The format now in use traces back to the mid-1980s. BMW engine codes are designed to provide a lot of information about the engine design and technology in a short amount of space. Standard BMW engines use a "M", "N", or "B" code. BMW M GmbH models use an "S" code. The official motorsport race engines use a "P" code.

Click on an image below to view the breakdown for each engine family.
 

BMW Motorsport S Engine Code Key	BMW M Engine Code Key	BMW N Engine Code Key
BMW B Engine Code Key (2020 version)	BMW B Engine Code Key (2023 version)

Surprisingly, BMW does not often play by its own rules and follow its own corporate logic. The technology is changing so often that even the internal logic can't agree. We've listed several engine code keys above but acknowledge there may be several other variations out there.

BMW M GmbH were also slow to adopt newer code logic. S engine codes roughly use the format of the M engine key all the way up to the S63 engine in 2009. After the S63 the S engines more closely follow the corporate code key from the N engines.

PHEV (Partial Hybrid Electric Vehicle) use an additional powertrain code for the engine + electric motor. We haven't seen a key that explains the code but it will start with "XB1". For example, the G20 330e has a "XB1142O1" powertrain consisting of the B46 gas engine and GC1P25M0 electric battery/motor. So far, all PHEV vehicles use a mostly-standard B-series gasoline engine with an additional electric battery and motor so the "XB1" code is largely irrelevant when shopping for engine parts.

Occasionally you will see engine codes that don't match the above keys and this is usually BMW using a shorthand abbreviation of the code. The "N52N" is commonly seen in BMW documents and referenced on sites such as RealOEM. For whatever reason BMW stuck an N on the end in 2007 instead of the more logical N52B30M0 (which is also referenced on BMW documents but is a mouthful to say). Our guess is they wanted to separate it from the slightly different N52K and N52O engines found in 2006 models. BMW will also sometimes combine new and old engine keys, such as an N63TU instead of N63T1. TU stands for Technical Update and indicates a new engineering feature. We can only speculate this is a habit from the old M code days when major revisions carried a TU suffix (M62TU) and BMW can't completely abandon it. 

 

BMW Chassis Codes

Jump to Model Details:

The E code system we use today began in the mid-1960s with the development of the E3 'New Six' sedans. The 'E' stood for Entwicklung, which is German for "development". The number advances with each new model project. Not all E-chassis are production cars, even concept vehicles may receive an E code. By the late 2000s all of the E codes were used up and BMW switched to F chassis codes, which were replaced with G chassis codes just ten years later. The short span of F chassis codes can be attributed to the proliferation of codes for various body styles. It wasn't until the mid-2000s that BMW used a different chassis code for different body styles. Now a coupe, sedan, cabrio, and wagon have different chassis codes even though most of the engine, driveline, brakes, and suspension are all shared. It saves time by having more information and a shorter code. There were just as many F chassis models in ten years as there were E codes in the previous 40 years!

The BMW CLAR chassis is not the same as the chassis code. CLAR (Cluster Architecture) is a modular engineering platform with components that can be spread among various models (further subdivided into classes, such as UKL and GKL).

BMW model years traditionally begin in September of the previous year. A 2012 328i would be released in September, 2011 (9/2011). However, BMW often "pre-releases" models earlier in the year, especially for a facelift (LCI facelift) or for major updates. This is usually done in March or July. For example, the 2011 E92 335i, which received the new N55 engine, was released in 3/2010 but as a 2011 model. When ordering parts we may ask you for a VIN to confirm the model and any other vital information.

The rest of this page is a listing of all BMW models and their engines for the US market (along with a few interesting Euro models). This should be especially helpful when shopping for BMW parts or material to use as BMW trivia!

Epilogue

A few bits of BMW trivia, facts, and figures (to keep you on the page).

1. Everyone believes the BMW roundel emblem is a "whirling propeller". That idea came from BMW advertising in the late 1920s. The emblem predates that advertising campaign and actually represents the official colors of Munich.

2. You might think that the last two numerals in a BMW model represent its engine size. And in the past you might be correct. But since the late 1990s the badge represents the power class. BMW has had a long tradition of bumping up the displacement for turbocharged models. And now that every BMW engine is a turbo the naming logic continues. Examples:
- E23 745i uses a turbocharged 3.2-liter engine (M102/M106). The logic dictates that the new turbocharged engine output equals a larger, 4.5-liter engine.
- E46 323i uses a naturally-aspirated 2.5-liter 6-cylinder engine (M52TU). But it's 169hp keeps it to a "23i" classification. Note the later E46 325i also uses a 2.5-liter but with 184hp.
- E90 325i/328i/330i models all use a naturally-aspirated 3.0-liter 6-cylinder engine (N52) but because they all had different power outputs they received different model names. 25i = 215hp, 28i = 231hp, 30i = 255hp.
- E90 335i uses a twin-turbocharged 3.0-liter engine (N54/N55) that, theoretically, puts out the same horsepower as a 3.5-liter engine.
- F44 M235i uses a turbocharged 2.0-liter 4-cylinder engine, yet carries a "35i" badge. There are two things at play here: one is that it's part of the M Sport line of cars, so it's a high-performance model. Two, is that its B48 engine puts out 300+ hp, which puts it into the "35i" power class.
- G20 M340i is not a 4.0-liter but it's 3.0-liter single-turbo engine has the same theoretical output that a 4.0-liter would (382hp).

3. The S70 engine used in the McLaren F1 is not the same engine as used in the E31 850CSi or M8 prototype. This is confusion and misunderstanding of BMW's engine codes. As explained at the top of this page, S is the prefix for a BMW M Gmbh engine, developed by M engineers (Paul Rosche). 7 is the code for a V12. 0 identifies the development phase of the engine (0-9). By code alone all engines in the F1, F1 GTR, 850CSi, and M8 are "S70" engines but they are not the same engine. BMW could have done a better job at naming the engines, S70, S71, S73, S74, etc. They did try to distinguish them with S70/2 and S70/3 designations but the suffix is easily dropped, leading to confusion.

The F1 and E31 M8 engines are very close - step-brothers perhaps. The timelines align very closely and they likely have much in common. We haven't been able to confirm all of the specs but we believe the M8 has: 6.0-liter displacement, 24-valve heads per side, coil-on-plug ignition, individual throttle bodies, and a dry-sump oil system. But Gordon Murray and McLaren determined that the M8 engine was too large and heavy. Ever the innovator, Rosche said, “We'll do a new engine.” At the time, Rosche already had the E36's Euro S50 engine under development. The S50B30 engine shared these technical features, and added VANOS variable valve timing. The visual similarities between the S50 and S70/2 are obvious. The S70/2 looks very much like two S50s siamesed together. The M8 S70/1 is very different, even with the limited photos available. All of those features are absent on the 850CSi engine.

This doesn't make the CSi engine any less of an ///M product. It was built by M engineers and produced by BMW M. and remains a powerful halo model for the E31 line. The M8 engine is not the same as used in the F1 but its technology and ideas migrated to the McLaren customer program and then found their way into the Euro S50 (which then became the S54). The M8 has become an important, but misunderstood, stepping stone in the development of the F1 and other Motorsport engines. While the F1 has became the most-famous member of the S70 family and it's DNA came from the very best of BMW's engineering talent. Tips of the hat to Hagerty Insurance, BMWBlog, Peloton25, and the McLaren F1 Driving Ambition book for the extensive background and inside knowledge.