What ever you do, do it well. Do it so well that when people see you do it they will want to come back and see you do it again and they will want to bring others and show them how well you do what you do.
If you say you want to automate cars and save people’s lives, the skills you need for that aren’t taught in any particular discipline. I know – I was interested in working on automating cars when I was a Ph.D. student in 1995.