According to Delaware Online, Musk recently told a Delaware audience (really, Delaware?) that, while he hopes Fisker succeeds, he has "some reservations about the feasibility of Fisker's approach." Why? Because "Fisker is very far from overcoming those [engineering obstacles to build an electric car]." Subtle.
This isnt' the first time there's been contention between the two. In courtrooms last year, Fisker and Tesla fought a battle over insider information that ended with "complete vindication" for Fisker. We'll see if this latest dis causes any further comment from Fisker – a company not known for taking it lying down.
[Source: Delaware Online via earth2tech]