I have been designing, manufacturing and selling cupholders for the BMW Z3 for over 20 years. The question I get is usually something along the lines of: Why can't I get a bigger cupholder in my car?
There are quite a few factors limiting the size of the cupholder. But first, let's go back in time a bit. While the Z3 was released as a 1996 model, it was designed in the early 1990's. If the internet is to be believed, the design was locked in 1993. At the time, BMW was a much different carmaker than they are today. The mentality was not one of luxury, but one of speed and handling and purpose. Why have a cup in the car when you should have two hands on the wheel and be driving flat out on the Autobahn? Indeed, the cupholder was an afterthought in the Z3 - it was an accessory introduced for the US Market after the release of the car.
Next, let's look at the Z3 interior. Scratch that, let's start by looking at the Z3 as a whole. Look at how small it is. It is an engine, 4 wheels and 2 seats. That is pretty much it. There is no room in the car for fluff. The distance between the driver and the passenger is under 7". Where can a cupholder fit in the car? Again, this was the early 1990's. This was before pop out cupholders in the dash.
To put a cupholder in the car, and more importantly, to make it functional and usable, it needs to be placed so a driver is not distracted trying to use it. The best spot is in the center console. Again, think about the center console of the Z3: it is about 7" wide. Add to this that the handbrake is there (having an electronic parking brake button won't come around until 2001). So with the handbrake, that 7" shrinks in half - to 3 1/2". That puts the maximum size of any cupholder at less than 3 1/2" as you have to account for the design of the cupholder and the material it is made of.
BMW offered a few options for cupholders throughout the life of the Z3.
These were just the cupholder options that BMW offered. They also offered a cassette holder and nothing, just an open rectangle. The only one BMW still offers is a revised version of the 2 Cupholder Armrest.
In every case, the cupholders were designed to be as big as possible. However, you are working with less than 3 1/2" so fitting anything larger than a soda can was going to be a feat of engineering that matched what went into designing the car itself.
In 2002 or 2003, we designed the Large Storage Base. We wanted to offer a single cupholder and the largest amount of storage space we could. We pushed the cupholder as wide as we could. In the end we got a cupholder that is 2 13/16" wide at the top and tapers down to 2 1/4" wide at the bottom. This will comfortably hold a coffee from your typical chain store, a bottle of water or a 12 ounce soda can.
The new version of the 2 Cupholder Base from BMW is slightly better for larger drinks. It has a removable ring that is 2 11/16" wide and once removed, the opening is 3 5/16" at the top. The cupholder still tapers down to 2 1/4" at the bottom.
So that brings us to another question I get: Why won't my BIG cup fit in the cupholder? Cupholders like Yeti Ramblers just won't fit in the Z3. They were not in the market in the early 1990's and, to be honest, the car is too small for many of these kinds of cups.
I offer the Large Storage Base and the BMW 2 Cupholder Base. There may be other alternatives out there that will fit a really big cup, but cups like the Yeti are close to 3" wide at the base. It is going to be really hard to find a usable space for a cup this big in the Z3. My suggestion is to find the cupholder you like - One that is comfortable and fits your storage needs. Then find a cup that works with that cupholder. Or live like a BMW engineer in the early 1990's, 2 hands on the wheel and driving flat out.