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

Of all of the makes and models on offer in years gone by, BMW's naming conventions were the easiest to understand. They arranged a seemingly complicated construct of numbers and letters very Germanly. It all made perfect sense: the first number was the model range, followed by two numbers that, in most instances, denoted the engine size. This was followed by a letter, with 'i' implying the inclusion of a fuel injection system and a 'd' indicating that it ran on diesel fuel. While it has remained largely similar, with the first number denoting the model series, the subsequent two numbers no longer indicate the engine capacity.

Related: The 8 best similar cars to the BMW 3 Series

It's that first number that we're interested in today, though, the number that tells you what model range you're looking at. If you're unsure of what the numbers mean, we'll dive into a breakdown so you can start making sense of it and discover the difference between a BMW 3 Series and a BMW 4 Series.

BMW Model Ranges

BMW follows a relatively simple formula most of the time: The first number in the model designation indicates the model series, with the odd numbers indicating a 4-door model range and the even numbers indicating a 2-door model range. While this is true for many of the series, there are a few exceptions. Here's a loose, high-level look at the BMW model ranges.

BMW 1 Series

The BMW 1 Series is the smallest of the BMW range. First introduced in 2004, the 1 Series included a series of 5-door hatchbacks. The exception is the BMW 1 Series coupe, which is convertible and attractive, compact with a small rear boot section.

BMW 2 Series

The BMW 2 Series is a compact car, a spin-off of the 1 Series coupe, introduced in 2014. Primarily a 2-door coupe, the 2 Series Gran Coupe and 2 Series Active Tourers broke away from this, offering a compact 4-door sedan and a front-wheel-drive MPV.

BMW 3 Series

The 3 Series is one of the most popular and best-selling BMW model ranges of all time. Launched in 1975, it replaced the 02 Series and was available as both a 2-door coupe and 4-door sedan. Larger than the 2 Series, South Africa mostly saw the 4-door variant, but certain years did offer a 2-door alternative. This was up until 2013 when the 4 Series was introduced.

BMW 4 Series

In 2013, the BMW 3 Series coupes and convertibles were separated from the 3 Series lineup and given their model line. As with the 1 and 2 Series, the 4 Series implies that it is simply a 2-door version of the 3 Series. BMW confuses things again by having a 5-door liftback variant called the Gran Coupe.

BMW 5 Series

The 5 Series is an executive sedan, somewhat larger than the 3 Series. Sporting 4 doors and a sizeable boot, the 5 Series remains a popular choice for the discerning customer looking for a premium product but still wanting to be involved in the driving experience.

BMW 6 Series

Much like a cat that doesn't know whether it wants in or out, the BMW 6 Series has come and gone over the years. First built in 1976, it was only a 2-door coupe. This line was discontinued in 1989 but reestablished in 2004 with the second-generation 6 Series. The model range continued through another three generations before the BMW 8 Series ultimately replaced it. Aside from the 5-door liftback Gran Coupe, the 6 Series was always either a coupe or convertible.

BMW 7 Series

The 7 Series has been BMW's flagship luxury offering since 1977. This premium 4-door sedan is usually the first model to receive the latest innovation and tech that BMW has developed before filtering it down to the smaller model ranges. 

BMW 8 Series

Relatively uncommon, the BMW 8 Series is a range of GT coupes first made in 1990. Sporty designs and proportions, paired with large, powerful engines, made the 8 Series highly desirable. The second generation offers a 4-door Gran Coupe, replacing the 6 Series in its entirety.