Machines that seem simple but actually aren't

An automobile motor may seem simple but actually is not. It is basically a crankshaft that drives pistons which transfer power to the wheels. But there are many processes involved like the timing of the spark from the spark plug that must be right on to ensure smooth firing of the cylinders, the right mixture of gas and air supplied by the carburetor, and the correct functioning of the fuel pump to supply fuel to the cylinders for example.