Very well put. Thank you for the info!
Just some perspective...let's examine a pretty basic component of a car, the door handle and latch system. Toyota, Mercedes and other long established automakers have designed, engineered, tested, produced, and repaired these systems for years and years. Mature, well understood. No real surprises, and they can evolve/modify the system with a certain level of confidence based upon the collective wisdom and data they have accumulated. Elon tells his Model S designers and engineers (many with no automotive legacy) that they have a clean sheet of paper, but that he wants exterior door handles that automatically extend and retract. So the engineer sits down at his desk/computer:
If the handle needs to move in and out, what is the actuator? Solenoid? Motor?
If the handle is extending/moving out, then how does the handle open the latch? Probably can't be a mechanical linkage like other auto marks. So you need an electrical system with an electrical latch.
But you want a mechanical backup to be able to open the door from the inside if the power fails or the electrical system fails.
So you need a 'dual' electromechanical system. In the S, the latches for the front doors are in the doors, and the inside handle has an switch to open the door but also a release cable for the mechanical release. FWIW, for the back doors, the latch is on the C-pillar (not the door itself like other auto manufacturers), and there is a release cable from a point under the seat bolster.
OK, so maybe you have figured out that you want a motor to drive the door handle in and out. Direct drive? Stepper motor? Gears? How big? Torque needed? Number of cycles before it fails (MTBF)?
If you use a motor, how do you set the handle extend/retract limits? Stepper motor--count pulses. Otherwise you need limit switches or something to stop the motor actuator from running.
OK, so the handle extends. How to actuate the door latch? In the S, the engineer has a microswitch that is activated when you insert your hand into the handle and pull a bit. How do you calibrate this switch? How much force? And you need a spring mechanism to retract the handle off of the microswitch when you let go (and also retract the handle when the motor is de-energized).
Do you need a micro controller to handle all of this? You need power and wiring through the door pillar and into the door. You need a CANBUS setup so that lock/unlock can be controlled centrally.
OK, so now you need to package this all up, keep it clean and dry, especially inside the door where it will get exposed to moisture.
Have I lost you yet? So with the Model S, those of us with older builds have the early revisions of this door handle/latch system. There were/are several failure modes. Early systems had a wire running to the microswitch that was routed in a way that the wire flexed over and over every time the door handle extended or retracted, and the wire broke. Early systems had a cast metal pivot gear attached to the mechanism, and this metal can become fatigued and fail, so that the door handle won't extend (the spring keeps it retracted), and the motor keeps running. A few folks have seen the reduction gear attached to the motor shaft itself fail. A number of folks have the 'phantom opening' event, where if you put the S into Park and the handles extend, one handle extends just a bit further than it is supposed to, and it hits the microswitch and the door pops open.
So in the 2013 S85 I just sold, I had 2 or 3 door handles either replaced (this was done early on), or repaired (now pretty common). My wife's 2015 S70D has had 3 repaired, last one today (failed yesterday, and the Ranger came out today with his repair kit with a new pivot gear, new weathertight seal, etc--20 minute repair). There are newer revisions/builds of the handles, however I do not know the current failure rate. Note that the Model X and 3 do not have this system. They do have flush handles, but a different way to accomplish the same end---to open the door.
There is a learning curve. Maybe the engineer began designing the handle/latch system in 2010 for the original 2012 Model S release (Signature cars). Did the engineer/Tesla actually run a suite of destructive tests to beat up the handle until it failed? Not a whole lot of time to have real world testing (maybe 6 years). Remember, Elon said that 'building cars is hard'. There have not been too many new car manufacturers in business (...still in business) lately. Lots to learn.
