I initially was contacted by a recruiter after talking with a former colleague. I had an initial interview with the recruiter; one week later I had an interview with the hiring manager; I finished my phone screens with an engineer working on a related system the proceeding week. Promptly following my last phone screen I was contacted and had an on-site interview scheduled for the next week.
The on-site interview consists of meet-and-greets with your HR contacts, a technical presentation (this is where you can clearly distinguish yourself from others!), then 5 one-on-one interviews. I LOVED THIS...from my former automotive OEM experience, I was challenged to think in new ways and presented with present problems. There is no way to prepare for this, and you will show if you know what you are talking about because...IT IS HARD. I still remember answering a question and then asking, "did that answer it?", to have the interviewer respond, "that's perfect." Think like an engineer...do not back yourself into the STAR method...that has no place in an engineering workplace!
...this is where the interview process slowed to what seemed like a halt...
I talked with HR and it was going to be nearly 3 weeks to find out what the next steps would be (essentially, they cannot just interview one person). So, after interviewing multiple candidates they decided to continue; you must answer a series of questions that will be reviewed by the CEO.
Once the CEO reviews the question, you get the final approval/non-approval. This process takes nearly 2 weeks.
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The people are VERY busy, and this job requires PASSION. You do not go to Tesla with money at the forefront of your mind, but if you left another automotive OEM, you go to Tesla for the opportunity to work on something where you know you will impact people's lives. If you go to another automotive OEM, you will likely have a cake-walk...my perception from talking with people during the interview is that it is FAST-PACED, fun, but challenging.