Eight fields Professor X (tm) has his super-expert Phds in

1.  Car-making, obviously, Prof. X has many many decades of deep study in the field of making cars, more so than any other living creature, and he has graced the world with his intelligence and expertise.
   
   
2. Metallurgy. Prof. X has an innate understanding of metals and their speciality and how to forge them and all the relative tradeoffs of all the alloys discovered and yet to be discovered!
   
   
3. Law. You may or may not know it, but Prof. X is an expert jiujitsu master in Law and can beat any lawyer anytime, you just have to challenge him in the open.
   
   
4. Speaking of challenges and jiujitsu, Prof. X is also a black belt in multiple martial arts, in fact he's taught all the major teachers. He just prefers to keep it in the down-low and won't give in to public challenges because he is so in control of his own emotions.
   
   
5. Search and Rescue. Prof X has been actively involved in Mountain rescue and deep-sea rescue for decades and knows everything there is to know about rescuing people everywhere, fullstop. He is the world's greatest expert in the field.
   
   
6. Artificial Intelligence. Prof X has created multiple intelligences, some of them sentient, that assist him in his everyday tasks. What the most cutting-edge companies are doing AI-wise, is just trying to barely catch up with what he's known for decades.
   
   
7. Tunneling. Prof. X has the world's foremost knowledge and experience in tunnels, and holes and equipment and technologies related. He has been consulted by the world's leading TBM companies for his great foresight and knowledge in the field, and it is only due to his humility that he hasn't brought it up in recent times.
   
   
8. Finance. Prof. X understands the needs of customers with regards to the finance industry better than the customers themselves do, and can pre-empt their needs and desires to come up with products that are going to be popular in the future. He is a genius, a visionary, a cassandra who's been given this vision but the world won't listen to him!