I just found that Spiritmonitor has 21 Tesla's logging with an average of 7.79 miles/ kWh.
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Overview: Tesla Motors - Model S - Spritmonitor.de
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and there is 1 2010 Zero model S logging there at 20 miles/ kWh.
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Electricity consumption: Tesla Motors - Zero S Modell 2010 - Spritmonitor.de
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But both these numbers seem way too high.