Taken from Dr. Zoidberg’s post: Really at this point the bigger the number = moah powah, across the board and nothing really beyond that. The specific numbers are meaningless other than to try to convey some sense of relative power and positioning within the model type. The number may be kept for “historical” reasons to convey improvement over a previous model that may have had a bigger engine but lower output (thanks turbos!) or just for better marketing position.

BMW: The “i” denotes fuel injection, but since literally every BMW has fuel injection now literally every BMW is now an “i.” At least they stick to their guns like that, and also provides a little bit better marketing indicator than just an anonymous string of numbers. The “x” denotes AWD, likely chosen as it’s a common industry indication of AWD (as in “4x4,” also the letter “x” can be seen as being graphically representative of an AWD setup connected to all four wheels at each corner). This actually predates their use of the term “XDrive” and it’s where “XDrive” actually comes from in the first place. Hence, all of their SUVs are X-something-i, with the number usually denoting a relationship with a corresponding car model. You also have the letter “d” which denotes diesel.

Speaking of which, 3, 5 and 7 were chosen because they logically indicated where each car was positioned relative to the others within the BMW model lineup. I don’t know why those numbers specifically and not say 4. 6 and 8 but “3” was likely chosen to indicate the natural and logical successor to the 2002, and things just went from there, keeping odd numbers to flesh out a semblance of a logical naming scheme. By dumb luck it ended up naturally reserving the numbers 4. 6 and 8 for the coupe versions of the 3. 5 and 7 but it was hardly planned like that from the beginning (of course the 6 goes back a good ways though).

“M” simply comes from BMW Motorsport, which should be self-explanatory.

Audi: Once again, originally started out with random round numbers that only needed to convey the message bigger = better and be easy to remember and market. Sometime in the 90s they decided to name their cars the A4, A6 and A8 specifically in honor of stretches of the Autobahn, again also using specifically round numbers that are easy to remember and market and indicate bigger = better. Again, by dumb luck this ended up reserving the numbers 3, 5 and 7 for coupes (we’ll pretend the A7 is a coupe, it is more or less competing with the 6 Grand Coupe and CLS or whatever after all) except for the A3 which gets to also be a hatchback and full sedan (as there already is an A2 super-mini).

“Q” stands for Quattro (derived from the Spanish for four, natch), so naturally their SUVs are Q#, with again the number corresponding to a comparable sedan in Audi’s lineup. For whatever reason they decided to go with odd numbers for their SUVs instead of lining up perfectly with the sedan models. One possible suggestion is that it’s also trying to convey seating, i.e. a Q7 is a 7-seater.

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“S” and “R” (as in Sport and Racing) just convey, well, Sport and Racing, hence their high-performance models are the R/S4, etc.

Mercedes - like with BMW, the numbers represent engine power (not size anymore) relative to other engine options within that model. These days the numbers are more chosen for historical precedent and/or marketability than any true denotation of engine size.

The letters C, E and S have no meaning other than to suggest how each car relatively positions itself within the MB model range. Why they chose those specific letters I don’t know. Generally, the higher up the letter in the alphabet it is, the bigger the car. There are A and B cars that are the smallest cars in the lineup but we Yanks don’t get them, save for the CLA.

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Their SUV naming scheme is somewhat muddled because when they started out they had no idea the SUV game would explode the way it did (especially within their own model line) so it’s been somewhat haphazard. The M was the Middle SUV, with the large SUV being the...G? And the GL? GL actually meant “Lange (Long)-G” even though that car had almost no mechanical or engineering relation to the G itself. The G actually stood for Gelandewagon, which roughly means overland car, and was MB’s first SUV as we classically think of them (it’s actually Europe’s version of the Jeep). Now every SUV will be G for Gelandewagen, with a corresponding letter lining up with a matching car in MB’s lineup.

Otherwise the “L” stands for Lightweight and usually indicates the sportscar. Thus the SL was the S-Class Lightweight, or two-door sport model. SLK = SL Kurtz, Kurtz being German for Short (as in shorter than an SL) and the rest meaning “lol these people hink they’re buying an actual SL, suckers.” But seriously, the SLK was the small (short) sporty convertible to the regular SL, likewise the CLK was the small (short) model lineup compliment to the S-class based CL. Now why the S-class coupe was called the CL I don’t know, likely because SL was already taken but then CL makes people think it’s related to the C-Class. Most likely the C is for Coupe, even though it should be Koupe in German, oh well. That’s also how we get CLS - Coupe, Lightweight, S-Class, and so on to CLA. And yes, again, four-doors, I know.

4Matic is MB’s proprietary AWD system, just like xDrive and Quattro area also registered trademarks and proprietary systems. The logic behind 4Matic should be pretty self-explanatory. Unlike BMW, which is happy to just add a small lower-case “d” to the end of your car’s nameplate, or Audi which will just straight up tell you it’s a diesel, MB thought compelled to invent a whole new level of market speak BS with BlueTech. Why BlueTech? What does BlueTech even mean? I don’t know. The Tech part should be pretty self-explanatory (as in people will literally buy anything with the word “Tech” in it) and Blue possibly to connote technology. Yes, the name more or less means TechnologyTechnology, way to go MB. My theory is that MB went to the same idiots Hyundai hired and suggested that “Genesis” and “Equus” are names that actually make people want to buy cars and that there’s nothing wrong with having a luxury sedan and a boy racer performance coupe have the exact same name.

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UPDATE: AMGTech schooled me on what BlueTec really is:

It’s actually BlueTec, no H. It’s an exhaust emissions treatment system for diesels that utilizes Diesel Exhaust Fluid (or urea, or AdBlue as Mercedes calls it), as well as A diesel particulate filter, special catalysts, sensors, and software to reduce emissions. OTR trucks/tractor-trailers/semi-trucks/lorries all use similar systems these days, and so does most every modern diesel. Blue is Mercedes’ version of green, eco-friendly. There are multiple variations of BlueTec, and the early ones didn’t use AdBlue, and thus were only 48 state compliant.

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I still maintain it’s named for the same idiocy that brought us Genesis sedan and...Genesis coupe.