Is that even legal? Shouldn't commpanies that offer same products compete rather than cooperate?
This is just standardization. If one has something sufficiently better than the standard there is an incentive to defect and use it.
No, that's not the standard for a combination in restraint of trade. Controls on monopolies and abuses thereof are not the whole of anti-trust law.
EDIT: To be clear, I'm not saying this is illegal, just that the fact that it doesn't create a monopoly is not, alone, the reason why it isn't illegal.
Also keep in mind that this companies do not compete on most of the parts of a car, many of this parts are designed,created and sold by third parties, this third parties can make products for different companies. I assume that now there is not a sufficiently large number of companies building this electric cars parts or self driving hardware and software from which the car producers can buy this parts.
Sharing with all is completely fine. Sharing with selected one (or few) looks shady to me.
Think about it like this, Ford and BMW are collaborating to make better airbags , in future both companies customers will have more safety because of this so no BMW customers should be upset that the Ford ones also got better airbags. What about the other companies though? Some are making good enough airbags in their opinion, some are buying airbags from a third party that are also good enough.
I am wondering if there is a bit of Silicon Valley jelosy that this companies won't buy SV tech that includes the latest ML buzzwords, the thing is that cars had driver assist features before SV made the autopilot cool again.
What law would it break? Why wouldn't that imaginary law also apply to, say, mobile phone manufacturers who have entered into agreements to use each other's patents without specific permission or payments?