What is the most mechanically complex component of an automobile? Someone told me that an automatic transmission is more complex than an electronic microchip. I do know a tiny bit about auto mechanics, but not much. Manual transmissions are relatively simple, mechanically. It's called gear ratios. Back 30 years ago, the mechanics in automobiles were very basic and simple, and if you had the proper tools and technical know-how you could perform most of the repairs yourself. But today, it is almost imperative you take your vehicle to a professional repair shot to have it fixed. With today's vehicles, you have to have a degree in electronic engineering to repair one yourself. There are more chips in a modern car than there are in the computer I'm using.