Elon Musk and company haven't explained what led to the spike, although it's easy to see Tesla's more accessible lineup playing a part. The return of the Model S 60 opened the door to buyers who couldn't quite justify the previous EV line. A more affordable 2-year lease program likely helped, too. On the other end of the spectrum, the P100D variants of the Model S and Model X gave the spare-no-expense crowd a reason to take a closer look.

The surge hints that Tesla shouldn't have much trouble hitting its target of 50,000 deliveries in the second half of 2016. It's predicting that its fourth quarter deliveries will be as good or better than it managed last year. The big challenge comes in 2017, as it gets ready for the Model 3. Tesla will have to ramp up Gigafactory production and deliver many, many more EVs to eager drivers.