Agreed – FYI: Tesla Model S (and likely X and 3) vehicles use a locked-down gateway (offering specific API actions, which result in CAN communication, etc) between their Ethernet network and CAN [1]

[1] https://www.blackhat.com/docs/us-17/thursday/us-17-Nie-Free-... (page 19), https://blog.lookout.com/hacking-a-tesla

That's how it is on my car, but at the same time my car basically has no fancy electronics.

I understand software engineers pulling stunts like this, because there isn't actually a regulated engineering license, but I'd honestly have expected automotive engineers to be vehemently opposed to putting the stereo on the same system as the brakes.

It's not the software engineers that are the problem it's the automotive design managers who decide that there will be one computer and one buss.

The DOT should have standards for this stuff. Infotainment system shouldn't have control authority or share critical buses with the engine and braking/traction control system.

Sure there is, just not in US where everyone can make cards with software engineers written on them after a bootcamp.

http://www.ordemengenheiros.pt/pt/a-ordem/colegios-e-especia...

https://blog.vdi.de/tag/informatik/

I wonder if some of this is to do with weight reduction. To have seperate buses must add a lot of extra equipment and wiring.

This means more weight and more power required to operate the electrics and in turn means lower MPG, higher fuel consumption and a more expensive car to design and manufacture.

The net outcome is a less competitive car in a competitive market.

I've worked with software engineers working on the CAN bus, and I had the same questions as you. According to them it has to do with the amount of cabling needed as well as electrical interference. A car has a lot of cabling going all over (a couple of hundred meters in total was the number I got), and if you can put as much of it as possible on the same bus(es), you save yourself a lot of problems.

So I suppose weight could be a factor, but space seems to be the big one.

Well the obvious solution it to go wireless! What could possibly go wrong?

It looks like a CAN bus hub weights about a pound. That's negligible, considering I have about twice that weight in garbage sitting in my cup holders.

[1]: https://www.autozone.com/electrical-and-lighting/can-bus-hub...

How much does death weigh?

-21 grams apparently /s

I mean "a lot" in computer terms is like 4 lbs of equipment but since the brake pads on a truck weigh in at more than that I assume its not weight related.

This begs the question: how do you know this is true?

Well JD Power listed Fords MyTouch as the biggest customer complaint of 2011[0].

I think customers might know how messed up their car is.

[0]https://wheels.blogs.nytimes.com/2011/06/23/aggravating-myfo...

My post makes no sense. I replied to the wrong parent

Most modules have some feature or other that needs to communicate with infotainment or another module that needs to communicate with infotainment. Error reporting is the big one, but there's lots of little ones too. The brake module, for example, may be involved in tire pressure sensing, and also takes configuration for traction control and reports activation.

It's hard to find an appropriate segmentation for an air gap without sacrificing features, and most customers won't trade features for "security".

You are right of course. But still. Once you can talk over the CAN bus you can spoof pretty much anything, if I recall correctly. You could at least have some intermediary module on both buses that acts as a proxy. Then if someone hacks your radio they can't pretend to be the ECM.

Then again, this exact scenario actually happened and having an intermediary didn't help. https://www.kaspersky.com/blog/blackhat-jeep-cherokee-hack-e...

The infotainment system should only be allowed to read values from the modules related to the actual driving. Configuring things like traction control will just have to be done via a system separate from the infotainment system.

I understand that it a little wasteful to not use that big touch screen in the center console to do configuration of the driving experience, but there's no safe way to do so.

But the gauge cluster screen is connected to the infotainment system.

An air gap may not be viable, but you can place a firewall there. There is no reason for everything to be on the same bus.

> An air gap may not be viable, but you can place a firewall there.

No idea how it was one or two decades ago, but modern architectures certainly have one.

I can't remember the specifics, but the one I looked at was actually pretty beefy hardware-wise, it had three reasonably powerful cores, 1GB RAM, etc.

> There is no reason for everything to be on the same bus.

It isn't. They would run into bandwidth or (more likely) latency issues anyway.

> IMO there should be separate infotainment and hi-speed system CAN buses.

There are. IIRC BMW uses seven (anyway, several) different CAN buses, plus other bus systems for entertainment (MOST bus)