I have no idea. But anecdotally, it feels like more than 1,000. I spot a lot them. Assuming anyone could get regular access to a home charger or supercharger, the Model S is extremely compelling compared to the competition. In HK, it competes with regular low engine capacity E class or 5 series sedans on sicker price. In the US, it competes with cars like the CLS or even S class Mercedes or 6 series BMW. Running costs are MUCH lower, especially for anyone who is thinking of having a driver, where fuel costs are a much higher %age of the total costs of ownership.