What is the difference between a BMW 3 Series and 4 Series?

In their never-ending efforts to fill every conceivable market niche, BMW’s model line-up has expanded way beyond the relatively clear-cut distinctions which used to mark their model range. In fact, their range has expanded to the point where the differences between the various models almost come down to semantics, which might seem a bit confusing to the casual onlooker. But, once you look closely, there is some logic to be found.

Martin Pretorius

12 Dec 2023 · 15:16Buying a Car5 min read

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Take the complicated relationship between the 3 Series and the 4 Series as an example. While the 3 Series has been around for decades (it’s currently in its seventh generation), the 4 Series is a relatively new model, which only recently started its second generation. These two models are clearly related, but how exactly?

Up till the end of the fifth generation 3 Series (known as the E90), the 3 Series model name encompassed all manner of body style derivatives. You could get a 3 Series with 4 doors, or as a 2-door coupé, or as a station wagon, or as a convertible. All of these body styles have been around since the second generation (E30), when the 3 Series moved upmarket from being only a 2-door, entry-level model.

Changing the naming protocol

While there wasn’t really anything wrong with this system, BMW nonetheless decided to implement a new naming protocol, starting with the F30 3 Series. In future, all 4-door variants were to receive a designation starting with an uneven number (1, 3, 5 and 7 Series), while even numbers would be applied to the related coupés (2, 4, 6 and 8 Series). This simple change was intended to move the market positioning of their coupé models further upmarket from their sedan- and wagon counterparts, and it made some sense.

Except that this wasn’t quite how it turned out. The 3 Series range was indeed (initially) reduced to 4-door and Estate variants, and the first 4 Series to launch was a 2-door coupé (followed in due course by the convertible), but then matters turned a bit cloudy. The F30 3 Series sedan soon spawned a 5-door fastback “GT” variant (for those who didn’t want an estate car but needed more versatility than a sedan offered), while the 4 Series received a 5-door fastback variant of its own (named the Gran Coupé).

What’s the current state of affairs?

With the local arrival of the seventh-generation (G20) 3 Series early in 2019, the “GT” fastback was discontinued, and seems unlikely to return again. Internationally, the latest 3 Series is only available in 4-door sedan or estate forms, and that’s probably how it’s going to stay. We probably won’t get any estate variants on the South African market, going on recent history, but there is the possibility of the M3 Estate making an appearance in limited numbers.

Meanwhile, the first-generation 4 Series made way for the G22 (second-generation) model in 2020, retaining the 2-door coupé body style as this range’s mainstay, with the customary convertible- and 5-door Gran Coupé models following soon after the 2-door coupé appeared. But, while the new-generation 4 Series is great to drive, those gigantic nose kidneys do take quite a lot of getting-used-to.

They’re all related, though, which means that the cars spawned from the 3 Series platform still encompass a wide array of body types: 4-door saloon and estate (with 3 Series badging), and 2-door coupé and the convertible or 5-door fastback (with 4 Series badging).

Related: This 2021 review has all the information about the second-generation BMW 420d coupé.

How different are they really?

As with their predecessors, the latest BMW 3- and 4 Series are very closely related, but the differences between them are nonetheless more than skin deep. For instance, the 4 Series is wider and runs on a wider track, to give a more aggressive stance and sportier handling than its concurrent 3 Series.

There are other differences as well: In keeping with its upmarket positioning, all 4 Series cars feature frameless door glass and lower rooflines, giving them a sportier and sexier appearance, even though they’re largely identical to a 3 Series inside. The first-generation 5-door Gran Coupe was downright gorgeous (although the new one's gigantic schnozz makes it a bit more difficult to love), and both generations are very practical as well.

It’s worth considering how appealing the straightforward 3 Series sedan really is. Better to drive than it's been in ages, more spacious and comfortable, and loaded with the latest technology, the new 3 Series is a tour de force, and marks an emphatic return to class leadership. By the same token, the new 4 Series is a machine of note: all of the 3 Series’ goodness, even if it is wrapped in somewhat challenging aesthetics.

Related: We reviewed the 2021 BMW 420i Convertible in its natural habitat.

The electric alternative

In keeping with their drive towards electrification of their entire model range, BMW also released the i4: a 4 Series Gran Coupé with an all-electric drivetrain, instead of the usual petrols, hybrids and diesels. The i4 is available in South Africa in either eDrive35 M Sport trim or the M50. The eDrive35 produces 210 kW and 400 Nm for you to charge ahead with. Then you get the mighty high-output, dual-motor (and thus AWD) i4 M50, which is good for a sub-4-second 0 - 100 km/h sprint, thanks to combined system outputs giving 400 kW and 795 Nm.