Additionally, the Model X appears to be significantly faster than the similarly-priced Cayenne Turbo S.

Cayenne Turbo S (the fastest Cayenne model) does 0-60 in 3.8 seconds. [1] The Model X P90D also does it in 3.8 seconds, or 3.2 with the speed upgrade, which costs $10k on other Tesla models, [2] bringing the total Model X price to $152k to the Porsche's $157k.

[1] http://www.porsche.com/usa/models/cayenne/cayenne-turbo-s/ [2] http://www.teslamotors.com/blog/three-dog-day