Here’s a bit of automotive history: The iconic BMW 3 Series was originally available as either a 2-door sedan, 4-door sedan, coupé and later on even had a convertible (cabriolet) model.
In 2013, however, BMW deemed the best-selling BMW 3 series to be too getting too confusing for buyers. And to be fair, it was all over the place. So they took all the 2-door 3 series and re-branded them as the BMW 4 series.
So are the 4-series cars just the two-door versions of the 3 series sedan? The answer is kind of, but not exactly, since over time BMW have tried to distance the 4 series from its 3 series roots.
Despite their best efforts, the 3 series and 4 series still share a lot in common. Let’s take a closer look at what exactly separates these two bimmers.
Body Type Availability
The main difference between the 3 series and 4 series is in their body style availability.
|3 Series||4 Series|
|Saloon (4-door)||Coupe (2-door coupe)|
|Touring (5-door sports wagon)||Convertible (2-door cabriolet)|
|Gran Turismo (4-door sportback)||Gran Coupe (4-door coupe)|
As you can see, the 3 series focuses on 4-door/5-door body types whereas the 4 series primary focus is on sporty 2-door bodies (with the exception of the 4-door Gran Coupe).
Many people find the existence of the 4-door, 4 Series Gran Coupe particularly confusing as it messes up the idea of the 4 series being the two-door counterpart of the 3 Series. But it looks cool so let’s just leave it at that.
Under The Hood
The base 330i and 430i trims both share the same 2.0-liter, turbocharged inline-four petrol engine. This is matched with a 8-speed Automatic transmission that has automatic Sport and Manual shift modes. (Note that the 430i is also available with a manual 6-speed manual transmission).
Let’s compare the 330i with the 430i:
|3 series 330i||4 series 430i|
|Horsepower||255 hp||248 hp|
|Torque||295 lb-ft||258 lb-ft|
|Acceleration (0-60 mph)||5.6s||5.5s|
|Top Speed||130  mph||130  mph|
As you can see, the performance figures coming from these two models is almost identical.
However, the 4 series also has the 440i which sports a 3.0-liter Turbo inline 6-cylinder engine. To get the same V6 engine with in the 3 series, your only option is to go for the M Sport M340i, which costs considerably more since it is an M Performance model.
Exterior And Interior
The two cars are almost identical under the hood, but they look different from the outside.
The reason for this is that the 3 series entered its 7th generation (known as G20) in 2018. The 4 series, which is still in its first generation (F32), is based off the older 3 series F30. Expect the second generation 4 series to look almost identical to the current G20 3 series.
Body type aside, it is possible to distinguish the two cars by looking at the styling of the front and back alone.
The difference at the front is subtle, but the differences are much more obvious at the back, with the 3 series newer design looking much sharper.
Moving on to the interior, we find there are some subtle differences between the two. Again, the 4 series is identical to the previous generation 3 series, so it looks slightly more outdated in design compared to the new 3 series, but is not any less luxurious.
It shouldn’t be surprising that a 4-door sedan is more practical than a 2-door coupe.
Not only is rear-row seat access much easier, but the 3 series sedan can fit 5 (40/20/40 rear row seating arrangement) whereas the 4 series coupe can only fit 4 people. Passengers in the back of 4 series coupe also have significantly less headroom and legroom.
The 3-series offers more generous cargo space, with 16.9 cubic feet of space in the sedan’s trunk vs 15.7 cubic feet in the 4-series coupe. Of course, the 3-series sports wagon and Gran Turismo hatchback boast even more room for cargo.
Given that the 3 and 4 series are built from the same foundation, you might expect the 3 series sedan and 4 series coupe to cost the same when you pick ones with the same engine.
But alas, a new 330i starts at $40,750 whereas a new 430i starts at $44,950.
For starters, BMW make you pay a premium for buying a coupe as opposed to a sedan. This isn’t uncommon in the automotive industry.
Secondly, some of the standard features on the base 4 series are optional features on the 3 series. For example, LED headlights and a sports bumper are standard on the 4 series, but optioned extras for the 3 series.
Ride And Handling
BMW are associated with providing an excellent drive experience, and both cars do not disappoint. The weight is perfectly distributed on both cars, but the lower center of gravity and slightly more compact body makes the 4 series slightly better at handling corners.
Hopefully this has cleared up the fundamental differences between the BMW 3 series and 4 series.
Because the BMW 4 series hasn’t had a generational update yet, the currently available model is based off the older generation 3 series. If you want the latest BMW design, the 3 series is your only choice, otherwise you can wait for 4 series to catch up.
And yes, while BMW have done what they can to make the 4 series its own thing through subtle design changes, there’s no denying these two cars are very much of the same blood.