A few comments:
The contactors are a single point of failure in an EV, but modern ICEs have fuel cutoff systems that are activated in a severe accident, so a fault could cause them to lose access to their power source, too.
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The 12V battery in the Model S is under much more strain than the one in an ICE, because the vampire drain is roughly 1000x higher in the Model S (50W vs. 50 mW). This requires that the 12V battery drains and then is recharged much more than the ICE battery, which is only used a few times a day, when starting the car.
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In my nearly 40 years of driving, I've had only one incident where a failure left me without power while driving: an electronic ignition module, which had been replace just a month earlier, failed without warning in the middle of the road. So, in my limited experience, that's quite a rare occurrence.
My 2007 Camry Hybrid, purchased during its first year of production, was quite reliable: in 8 years and 120K miles there were no power-train or other failures that made it undrivable. In fact, it seems that the Prius/Camry hybrids, which replace the torque converter and transmission with a motor-generator torque/speed converter, are at least as reliable, and possibly more reliable than the similar ICE models. The hybrid reduces the demands on the ICE engine, and the motor-generator is both simpler and more reliable than the conventional transmission.
In contrast, in 16 months, my Model S has been serviced more than a half dozen times, sometimes for body issues (misplaced moldings, leaking seals, impact protection for the battery) and sometimes for drivetrain issues: a mis-installed battery connector, the proactive contactor replacement, and now, while the contactors are being replaced, they've decided to replace the drive unit. Only once has Tesla provided a Model S loaner: every other time they've offered to rent a car from Enterprise, which I usually decline as I have better options.
I've also had about three Ranger visits: once to try to fix the leaking reverse-light applique seals (eventually replaced at the service center), once to try to find and fix some annoying rattles (more were fixed later at the service center), and once to replace the 12V battery after it started asking to be replaced.
I guess it's a good thing that Tesla has just opened a service center only a two-hour drive from my home, making the most recent service somewhat more convenient that the prior 3+ hour trips each way.
I suspect that I've had more problems than average, and certainly more problems than I've experienced in my more plebeian vehicles, so I do feel that the car hadn't (in September, 2013) been built with the same level of experience and quality of more mainstream cars. Tesla has made up for this with exceptional performance, both on the road, and in the service department.
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More generally, electronic hardware tends to either work or not work (software is another matter). I expect that there are many single points of failure in the Model S, from the contactors, the cables and connectors, the motor control circuits, to the power electronics in the motor drive circuits. Just like my electronic ignition module of many years ago, I expect that an electronic/electrical failure could easily cause a complete loss of power. I take it on faith that Tesla's designers have sufficient margins in their designs that the MTBF is 10,000+ hours (a quarter million miles or so).
Note that if the MTBF is 10,000 hours, and there are 30,000 cars on the road an average of 3 of them will fail each hour. Dramatically oversimplifying, 3 of them will fail in the first hour of use after delivery, and a few dozen of them might have failed in their first week. So, some owners will have such unfortunate stories: statistics almost guarantee it.
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My experience is not "average". Neither is yours.
