Some car nerds like me might have noticed that car names aren't always logical, or, at one point lose their logic. I'll warn you beforehand, this is something I can go on about for hours, and it seems extremely boring to other people.
Now that I've warned you, let's start with discussing the BMW lineup. It's not very complicated, and it's in fact, very logical! It starts with the BMW 1 series, the smallest (normal) car they offer, and the cheapest one, too. It's a hatchback, it's affordable, and small. After that they have the 2 series. This is the one that makes the least sense, since they have 5 versions, there's the Coupe, Gran Coupe, Convertible, Active tourer and the grand tourer. In my opinion, the 2 series should only be the rather unflattering active tourer and grand tourer. Those are just second in line, just like the B-class Mercedes, and the discontinued Audi a2. After this model though, the lineup is back to being sensible and logical, namely the 3 series is the "normal" car, it's a middle class car offered as a sedan and as a wagon. Then we have the 4 series which again, makes sense (at least the number, I'm not going to get into the discussion of 4 door coupes) it has either 2 or 4 doors and a sloping coupe -ish roofline. Then there's the 5 series, which is built for the people that would also be in the market for a three series, but they prefer a little bit more comfort, and they have a little more to spend. It then also is a "normal" car which is either a sedan or a wagon. Next in line is the 6 series, which is to the 4 series buyer what the 5 series is to the 3 series buyer, in other words they want a 4 series, only they prefer a bit more comfort and have a little bit more to spend. In case of the 6 series, there is also a little more exclusivity involved, since we're now moving onto the higher end market segment.
The 6 series also used to be offered as a normal coupe and as the 4 door with a coupe -ish roofline. Now they've changed that, and they now only offer the, well let's face it "less than pretty" GT version, which is, well I wouldn't know what to call it, it's like an x6 slept with the 2 series sports tourer, and their baby slept with the 5 series. This I expect will also soon go away, since the 6 series is being replaced by the 8 series. This makes sense because let's face it, the 6 series, both as a gran coupe and a normal coupe, were the car you would get if you were in the market for a 7 series, but want something more interesting. The new 8 series is truly luxurious, and so I think that it definitely deserves it's name, and the 8 fits better than the 6.
This leads me right to the 7 series, which is a another "normal" car. That in the sense that it's a sedan with 4 doors. However this is the car for the person who wants the ultimate level of luxury BMW can offer them, yet still drive something with which they don't really stand out a lot.
Now for the sense making part
The car names can be seen as the basis, which you can't really mess up. Where car brands mess up is the SUV's. Now with BMW, like I said, the lineup is logical and sensible. The X1 namely, is the most affordable, and smallest BMW SUV, and the X3 is the normal, middle class version. Then there's the X4. Their Coupe -ish SUV. And then the X5, X6 and X7 also line up perfectly with the cars they are basically named after.
It doesn't seem like Audi understand how they should name their cars. I'm not going to discuss the a models, because the a series line up quite nicely with BMW, if you start at the a3 which can be compared to the 1 series and so on. The a2 is like the 2 series, but it's discontinued and the a4 is comparable to the 3 series and from there on out just add a number to each and you have the lineup. But with the SUV's Audi has gone a different direction, a rather illogical one at that.
The Q2 is a weird, small SUV which isn't really there in BMW's lineup. The only real competition that comes to mind is the Volvo xc40. Then the Q3 is on the one hand like the BMW x1, but it also covers the BMW x3 if you get the sportback model. Then you get the Q5, which should be named the Q4, because the a5 is the coupe, and the a4 is the "normal" car. The q7 should be the q6 because, again, the a6 is the "normal" car, and the a7 the coupe -ish car. The q8 should be named the q7, and the Q8 shouldn't even exist yet, since Audi don't offer a full size SUV (yet).
Mercedes has recently changed a lot in their lineup, and for the most part, it now makes sense. They offer a GLA, GLB, GLC, GLE, and a GLS. All based on the sedan model of the last letter. Now one could say that the GLC and GLE coupe don't quite make sense because they would normally go along with the CLA and the CLS, however, there are two problems with this. Firstly, how can you combine those names decently? GLECLS doesn't quite roll of the tongue, and secondly, the CLS is a stylish, beautiful car. I can't say the same about the GLE coupe. So Merc's lineup makes most sense after all, at least when it comes to names. The amount of models they offer on the other hand, is insane. There are 35 different Mercedes models you could currently get. Almost every single model has a coupe version, a sedan, estate, SUV, and a convertible.
I realise this article might be way too long, but I just had to write this down. If you have a different opinion on the logic, I'd be glad to hear it!