UPDATED
3 basic shapes explain all Apple products
Thoughts on Apple Car, Part 146
If you take all past and current Apple products, you find that the industrial design follows three simple rules for shaping all of them.
The principle best comes to light looking at all iPod models, which over the years have gone through all stages of the three basic shapes in iPod’s design evolution.

The three main shapes to be found in the image are:
- Extrusion with rounded corners and a sharp edge (see iPod on the left for vertical extrusion, others for horizontal extrusion).
- Rounded corners and edge with a sharp front (see iPod on the bottom, today’s iPod touch is missing but is the perfect example).
- Rounded corners and edges (see iPod on the bottom going in this direction, when not fully).
Let’s go into detail for each of the three.
Extrusion with rounded corners, sharp edge
This classic Apple shape is in use by so many of their products, but really started with the infamous Cube (introduced 20 years ago this month) and the original Mac mini that followed:

This shape has shipped in so many products, even the latest peripherals like the Magic Trackpad:

And the simple extrusion from a plain surface is what defined the iPad Pro when it really set itself apart from the greater iPad line:

This was a continuation of the iPhone 4 form factor, extruding towards the user. The sharp corners were its signature:

The principle has also been applied to Apple notebooks since the modern unibody aluminium models:

One noteworthy thing about the execution is that the extrusion can be vertical or horizontal. Whereas the Mac mini is extruded vertically and has its IO on the extruded side, the Apple remote for instance is has its user input on the other side, which in this case is the front.

The extrusion however can also be horizontal, with the UI on the extruded side, which in this case is the longer one and forms the surface of the device – see the clip-on iPod shuffle:

Back to the remote, there has been a variant of the TV remote that had a slight variation of the shape, sporting a bent rather than a flat surface.

Where a remote is a simple device, Apple’s most complex device, the Mac Pro, follows the same principle:

You see that this shape is classic millennium Apple.
UPDATE
The iPhone 12 also follows into this category:

Rounded edge and corners with a sharp front
Another classic one is the shape found in the very first iPod: It refines a simple extrusion with rounded edges in the back, a sharp edge to the front (display), and all rounded corners.

Also the first iPhone launched with this design: See the profile side-view photo, where the rounder back almost closes full circle to the front, but is still cut sharp in the steel frame around the display.

It’s a brilliant way to convey a slim and rigid design, so well done that is had been applied squarely to the iPad line, from mini to Air to the very first Pro.

With this design, it’s possible to make anything go away behind the display. A move the has been popularized in the post-2001 iMacs:

We will certainly see this shape continue to be heavily used in products that are all about the display.
Rounded edge with rounded corners
Finally, the shape that is now mostly used in the modern Apple design language, actually started in 2006 with the white MacBook:

All corners and all edges are rounded, resulting in a product that is as friendly and cosy to hold as can be.
The concept has been picked up for the Apple Watch case, which is almost perfectly rounded out.

It also extends to the Watch bands, that follow the lines of the rounded form:

Finally, all iPhones after generation six used this shape as the basic design.

iPhone 11 sports this design across the line, while we can expect that iPhone 12 Pro will adopt the extrusion shape of the current iPad Pro.

The question is how Apple will apply these principles in a more meaningful manner: While the iPod line went through all of them with no specific reason, the latest executions hint to a Pro use of the sharp-edged extrusion and a consumer use of the all-round finish.
By the way, there’s a recommended Hackernoo article about the way Apple rounds corners.
What will be Apple Car’s shape?
Based on the three basic shapes discussed above, the question is which one will be adopted for an autonomous car. There are so many things that aren’t necessary in a car once it drives itself, that the opportunity to reduce to the max are profound.
The other day I was driving on the highway and saw a few of those typical black vans carrying business people to the airport. They are square-ish in the back, covering the maximum of the some 2 meters width. If you take the driver zone and engine room away (both unnecessary spaces in electric autonomy), you’d end up with a simple box.
That’s what I think Apple Car is: An extruded box with rounded corners and a sharp edge top and bottom.
(see renderings in the link)
If the three basic shapes found in Apple’s past 20 years are any indication, we can have a pretty good guess what they’re going to use in the future.