3 stage process:
1) phone call screen with HR to ensure you are a real person
2) technical(ish) video call with a more senior mechanical engineer on the team I was interviewing with (mostly discussed resume; some basic technical questions as well).
3) onsite: Was asked to prepare a presentation about myself along with a previous technical work. Panel of roughly 8 engineers sat in and asked questions about presentation along with technical questions to determine my capability. Difficulty of questions varies dramatically based on the person asking questions, from softball questions to extremely difficult and nuanced questions.
Biggest negative to entire process is that getting your name in the door is a random lottery without getting internally referred.