HW4 (Tesla new self-driving hardware)

My new Model Y came with Hardware 4 (HW4), consisting of updated cameras and a new computer. Naturally I’m curious about what I got, and there is not a huge amount of information out there.

Cameras

The new camera suite has two visible changes: first there is one fewer camera, a change from 9 to 8. The second is that camera lenses have a red tint when you look at them. Four of the cameras record to the dashcam drive, and here I was able to make some observations:

HW3

• All camera’s file resolution was 1280 x 960. Typical 52-second video file size: 33 MB. Frame rate 36 FPS. Sample sum of all 4 camera’s file sizes: 101 MB.

HW4

• Front camera resolution 2896 x 1876. Typical File size 52 MB.
• Back camera resolution 1448 x 938. Typical file size 29 MB.
• Side cameras resolution 1448 x 938. Sample file size 25 MB.
• All cameras frame rate: 24 FPS.
• Sample sum of all 4 camera’s file sizes for 52-seconds : 132 MB.

While the resolution of front camera recordings are much greater with HW4, the other cameras are only slightly higher. The frame rate has dropped for HW4 from 36 FPS to 24 FPS. Overall one might to expect 30% greater usage of the dashcam drive.

The actual resolution of the cameras is unknown, at least to me.

A recent addition to Tesla firmware allows the owner to view all 7 external cameras plus the cabin camera through the car’s Service menu.

Computer

Tesla announced its then new Full Self-Driving Computer (what came to be called HW3) at its Autonomy Day event back in 2019. (Hardware 1 was a system based on a self-driving chip from MobilEye, now a part of Intel. Hardware 2 introduced in late 2016 used an NVIDIA graphics processor.) When Tesla introduced its first full self-driving computer, they mentioned that they were half way to creating a new one. The FSD computer has a massive amount of computing power, with Tesla proprietary neural network chips, general purpose computers on chips, memory and video processing. This computer also powers the car’s infotainment system.

The HW4 computer uses an AMD Ryzen™ chip for infotainment, making the touchscreen far more responsive. It also reduces the available infotainment RAM. A faster infotainment system is cool, but self-driving is the important thing, and here we don’t know much. A report on the computer from Munro and Associates notes that the new computer is faster and that there are 3 neural network processors, one more than with HW3.

Autonomous driving

Speculation abounds about the relationship of HW3 and HW4 and what it means to future Level 4 autonomy for Tesla cars. Elon Musk recently demonstrated an upcoming major revision of FSD (Version 12) on a car with HW3. He has also said on Twitter that HW4 software will lag HW3 by “at least another 6 months.”

But what does “lag another 6 months mean”? Today there are HW4 cars running Version 11.4.4 of FSD, which is on par or ahead of the large majority of HW3 cars. HW4 and HW3 can run the same software. What I think Musk is saying here is that HW3 cars and HW4 cars running HW3 software will get a production Version 12 of FSD in six months, and then Tesla will start working on a version that can take advantage of the unique features of the new hardware. And of course, Musk’s self-driving predictions are always late. Since V 11.4.4, there have been new versions of FSD for HW3, but not for FW4. Leaked release notes for V11.4.8 mention HW4, so perhaps that version will support both systems.

My recollection is that Tesla said at some point that the HW4 computer’s primary advantage was that it would be a larger multiple safer than a human driver than the HW3 is.

In a recent podcast with Lex Fridman, Musk said:

And there are a bunch of sort of fundamental functions that we kind of forgot to include. So we have to run … a bunch of things in emulation. We fixed a bunch of those with Hardware 4, and Hardware 5 will be even better It does appear at this point that the car will be able to drive better than a human, even with hardware three and a hundred Watts of power. And really, if we really optimize it could be probably less than 50 Watts.

Elon Musk – November 2023

One possibility is that Tesla still thinks that — that HW3 can reach Level 4 autonomy and be 10 times safer than a human driver, but HW4 would be 100 times safer [conceptual numbers]. Maybe they still think that, but it’s clear that Tesla’s view of the problem changed radically in the past few months.

Remember Musk in May of 2023 talking about V12 and excusing its delay, tweeted, “

Arguably, v11.4 should be v12.0, as there are so many major improvements. v12 is reserved for when FSD is end-to-end AI, from images in to steering, brakes & acceleration out.

V12, according to Musk now, throws out the 350,000 lines of code that made up those V11 dot releases and replaces them with machine learning. V11 is, plain and simple, perceived by Tesla as a dead end. (This is not the first dead end / restart declaration from Tesla on FSD.)

The problem Tesla has with saying much about HW4 is that there are [some big number] of HW3 cars out there owned by people who purchased FSD who will be VERY UPSET if it can’t reach Level 4 autonomy. If HW4 is necessary, then it’s in Tesla’s advantage to get it into as many cars as possible as soon as possible, but not to start a panic.

The alternate view is that HW4 just gives prettier dashcam pictures, plays games faster and costs less.