I love this question !!!!!!!!!!!!!!!!!!!!!!!!!!!!
The rule of thumb is, in terms of seat height, your head should be lined up with the middle of the windshield. Your chest should be 12 inches from the steering wheel. Your arm full extended, your wrist should rest on the top of the steering wheel. Steering wheel height, seat and backrest tilt, and lumbar support are up to you.
Personally, I sit with no lumbar support, seat height at close to the lowest position, seat angled up/back just a bit, and back-rest is tilted back just a bit. My steering wheel height is at a lower position, aimed pretty much at my chest but angled up just a bit. It is sooo hard for me to acquire the "perfect" seating position in a car, so when I finally find that special spot that satisfies my 100%, I never forget it. [fake]