I have a beat up, rusty looking, leaking windshield, door sticks, tail gate is jammed '87 Toyota pickup with well over 200,000 miles on it that we know of...
But, I can take the entire engine apart with a 10mm & 12mm socket, flat head & phillips screwdriver, and a hammer (ofr those parts that want to stick). And I am far from an engineer (my degree is in business) but I can change any part of this engine that goes bad in my back yard.
My wife's '99 Dodge Stratus, I can change the plugs and wires, give it an oil change, change the air filter and the head lights. Anything else and you almost have to drop the engine from the car to work on it. I've given people jump starts with 2006 and 2007 model cars and I couldn't identify half the parts under the hood on some of them.
The car companies are in cohoots with mechanics. They want to make it so you cannot work on your own car in your own backyard. Pretty soon, they'll come up with a way you have to take your car to the mechanic to do something as simple as change the oil.