Tesla Motors Inc. revealed disappointing financial performance in the fourth quarter Wednesday, but promised much brighter days in 2016, sending shares roaring back after a prolonged slump.

But can Chief Executive Elon Musk’s bold predictions for 2016 be believed?

To recap some of the promises Tesla TSLA, -4.14% made for this year on Wednesday:

– 80,000 to 90,000 cars delivered.

– Debut of the Model 3, Tesla’s promised “mass market” model, and start of preorders March 31, with the cars being produced and delivered by the end of 2017.

– Profitability on a non-GAAP basis and positive cash flow for the full year.

– GAAP profitability in the fourth quarter of the year.

– Production rate reaching 1,000 cars a day by the end of the second quarter.

– No need to raise more funds despite spending $1.5 billion on capital expenditures.

The forecast seemed to give the company’s investors reasons to believe again, and Musk reiterated his stance Thursday on the Model 3. Tesla shares Thursday regained a solid portion of the 11.6% loss they had experienced this week, part of a 2016 downfall for the volatile stock.

“We believe Tesla’s initial after-hours spike up, despite the shortfalls, is partly attributable to relief after the volatile shares fell 40%” so far this year, S&P Global Market Intelligence analyst Efraim Levy wrote.

However, Tesla has made similar promises in the past and failed to live up to them. Musk confidently predicted 55,000 deliveries in 2015, but eventually had to drop that number to a range of 50,000-55,000, which Tesla barely made. In 2014, the company predicted delivery of 35,000 cars, then lowered that to a range and eventually delivered less than 33,000.

Tesla also delayed the launch of the Model X more than once from early projections, and the newest Tesla electric automobile has rolled out slowly, with fewer than 300 deliveries in the first full quarter of availability. The delayed and slow rollout of that car is already causing skepticism about the Model 3, even among bullish Tesla observers, as resources still must be diverted to the Model X.

“This, added with the need to ensure the highest quality and most efficient manufacturing design on its lowest priced car, leads us to reiterate our expectation of a Model 3 launch in late 2018 (unchanged), at least 1 year later than the company is targeting,” Morgan Stanley analyst Adam Jonas wrote earlier this month.

Also see: Here are 5 things we now know about Tesla’s Model 3

Musk seems to have learned from previous missed forecasts by being less specific. His deliveries projection for 2016 is already a range, after previous forecasts had to be adjusted from a specific number to a range with that number at the top. However, even at the low end of the range, Tesla must increase its full-year deliveries by nearly 60% to reach its goal.

“If he gets in that range at all, it will be in the low end,” Kelley Blue Book analyst Karl Brauer predicted. “Its going to be very tough to hit that number. He’s got to maintain demand for the Model S along with producing all those Model X’s.”

Brauer, who correctly doubted Tesla’s inability to hit 55,000 deliveries in 2015, also questioned Musk’s claims of 2016 profitability. The analyst pointed out that Tesla delivered a record number of cars in the fourth quarter, but still had its least profitable quarter of the year.

“Sales and revenue are going up aggressively, but then costs go up too. In spite of a substantial jump in sales, profitability sank even faster,” Brauer noted.

Also see: Tesla ‘cash is king’ policy met with skepticism

For Tesla to reach its forecast for 2016, Tesla will have to execute near flawlessly with a lot of moving parts. The company is continuing to work on its Nevada “Gigafactory” for battery production that is key to the $35,000 price tag for the Model 3, and is still working on production lines at its Fremont, Calif., factory, which Tesla said has already been limited once this year to ensure quality.

“A lot of things will have to go right for them,” Baird analyst Ben Kallo told MarketWatch. “There’s a lot of details they need to execute on.”

If Tesla is able to realize its goals on its stated timeline, it could eventually reach sales (and profits) that justify its lofty valuation. Previous experience, however, suggests there will be some changes along the way.