Asked whether he believes Musk, who has failed many times to deliver on Tesla forecasts, analyst Colin Rusch said "no."
"We discount what he says pretty substantially," he added.
But Rusch said he's still a believer in the overall Tesla story because it's innovating at a faster rate than traditional automakers. "It's about the cool-car thesis," he said.
The electric car maker was not immediately available to respond to CNBC's request for comment on Rusch's criticism of Musk.
Electric vehicles are the future and they're fun to drive due to great handling and acceleration, Rusch said. And with traditional automakers slow to cannibalize their combustion engine vehicles, he thinks it's going to be hard for them catch up to on electric, despite the production problems plaguing Tesla's new Model 3 sedan, its first vehicle aimed at the mass car-buying market.
"If they solve the problem of getting a Roadster to … [space], they can probably do the same with providing guidance to us on timing. But they're not," Rusch said, referring to Musk's other company SpaceX, which earlier this week launched a rocket carrying a Tesla Roadster sports car to demonstrate payload capacity.