Go ask any automotive mechanic, I'm sure they would qualify to answer this question.
Not the same as a Ford engineer who might have been involved in the design and testing of the engines at manufacturer level..... Automotive mechanic, on the other hand, out of school at 16, 3 to 4 year apprenticeship on fixing cars and classroom theory, then many try to rip you blind when you want your car fixed and half the time don't diagnosis the problem right first time. ... okay I'm generalising