Three Series BMW, How it's Grown in Size & Weight.

It's a fact that cars have all grown in size since our youth. A VW Polo is now bigger than an old Golf and a new five is bigger than an old seven. But let's try to quantify just how and when the three series grew.

For this test I've chosen the mid-range 325i four door saloon or the nearest to it for a given E number. Sizes are in mm and kg, widths exclude wing mirrors. Bear in mind that weight depends on the options fitted and that some, such as aircon, are quite heavy (up to 40kg on older cars). For the E21 I've had to use the two door 323i.

BMW E21 dimensions

E21 dimensions.

Model Version Length Width Height Weight Weight Gain
E21 323i 4355 1610 1380 1190
E30 325i 4325 1645 1380 1200 1%
E36 325i 4433 1698 1393 1370 14%
E46 325i 4471 1739 1415 1460 7%
E90 325i 4520 1817 1421 1495 2%
F30 328i 4624 1811 1429 1505 1%


Let's start by admitting that some of the weight gain is due to the options that are now standard. ABS was optional on the E30 but standard on the E36. Similarly with aircon on the E36 and it's standard fitment to the E46. We must also recognise that 14" wheels with 195 tyres are an awful lot lighter than 18s with 255s - just try changing a wheel on a modern BMW and you'll see what I mean.

With that in mind much of the weight came came with the E36, no surprise there as it's a larger can than an E30 but it's only 2.5% longer and 3.2% wider. Much of the extra weight came with a stronger body and more standard equipment. Even the more complex multi-link Z axle rear suspension added it's share.

What is surprising is that the weight gain seems to be slowing drastically. Partly this is down to materials, the lower control arms on the E36 were steel but are aluminium on the E46. Electronics are now smaller and need smaller housings. Miles of wire have been replaced by the CAN-BUS and other systems. But also the list of equipment has not grown that much in terms of physical devices. Many of the new bells and whistles on the F30 are just software differences over older models.

One reason I wrote this is for my own research into the E90. I think my E46 touring is a bit big although I like being able to throw my road bike in the back. My E36 touring felt a much nicer size but it seems that's not supported by the numbers. I've been put off an E90 as it just looks a lot bigger, especially when I park next to one. But it seems the E90 isn't much heavier, it's about 50mm longer and a disappointingly large 80mm wider. The width is a factor for me as I drive on a lot of very narrow single track roads, come round a blind corner on one face to face with a large truck and a narrow car suddenly very desirable! An E90 is over 170mm / 6" wider than my E30 and I don't like that. So is an E90 for me? To be honest, I'm not sure. I think I'll go and look at some E46 325ti Compacts first.

The driving factors behind the growth in weight have been increased crash protection requirements and the extras that are now standard. Consumer demand (or BMW's perception of it) has been the reason for the growth in size.

BMW E46 dimensions

E46 dimensions.