It's really weird, I create another project to sent to you, when I first used the LWRP Spine Material the problem was there, so I change to a unity lwrp shader and the batch worked, I change back to spine shader and it worked too... but now inside my original project I tried to simulate the same steps, but doesn't work. I don't know, but it seems to be a problem with the LWRP. And I can't send the problem because only happen with my original project.
Alright, after I deep looking, I discovered that the difference between the two projects was the LWRP Settings, so the problem is with the Shadow Cascades, if I turn it off it doesn't batch, I need to put at least Two Cascades, probably a bug?
Well, with some cars it works, with other don't, I am completely lost right now haha.