PALO ALTO — After suffering under the weight of two car fires that sparked a federal investigation, Tesla Motors (TSLA) stock rebounded in a big way Tuesday after the electric-car maker announced that a German safety inquiry had ended with no concerns and a big-name auto analyst suggested shares were now “undervalued.”

Tesla shares shot higher by $20.53, or 16.5 percent, to $144.70 Tuesday, reversing a downhill ride that took the stock from a record intraday high of $194.50 Sept. 30 to as low as $116.10 in late November, a decrease of more than 40 percent.

Tesla’s decline has been alternately blamed on concerns about two Model S fires in the United States and the stock’s spectacular rise, which led CEO Elon Musk to admit that Tesla has “a higher valuation than we have any right to deserve.” Good news on the first front arrived Monday afternoon, when Tesla announced that a German investigation into the fires had found “no manufacturer-related defects.”

The fires in Washington state and Tennessee occurred after metal debris in the road punctured the underside of the drivers’ Model S electric cars, eventually causing the cars’ batteries to catch fire and engulf the cars in flames. A third fire, in Mexico, occurred after a driver drove through a concrete wall and slammed into a tree.

After the National Highway Traffic Safety Administration announced last month that it would investigate the Model S “to examine the potential risks associated with undercarriage strikes,” Musk vociferously defended the company in a release the same day. Musk wrote that Tesla had issued a software update to its cars that will keep the underside of the car farther away from the road during highway driving and promised to amend Tesla’s warranty policy to provide coverage for any fire, including blazes caused by driver error.

Tesla has been expanding delivery to Europe and Asia, and Musk recently described Germany as “our top focus in the world” for the Model S, the first car the Palo Alto company has fully developed and manufactured. A Tesla spokeswoman said by email Tuesday that the German investigation did not have any effect on sales in Germany, which “have been proceeding smoothly.”

Before the fires began affecting the stock price, Tesla shares had shot up more than 470 percent in 2013, as the company showed off its first quarterly profit and ramped up production of the Model S to meet increasing demand. The stock’s sudden gains caused many stock analysts to urge caution, but well-respected Morgan Stanley analyst Adam Jonas said in a Tuesday morning note that the recent slide had reversed his views. Jonas tabbed Tesla as the investment bank’s top stock pick among 26 U.S. automakers and noted that “Tesla shares have moved from 20 percent overvalued to nearly 20 percent undervalued in just two months.”

“We are actually impressed there have only been three fires since the car has gone on sale over 17 months, 22,000 units and some 130 million miles driven ago,” Jonas wrote, later adding, “Investors who resisted buying into the momentum peak have a new chance to own a good and well-managed company.”

Other analysts were more cautious Tuesday, preferring to wait for the end of the NHTSA inquiry to declare a success for Tesla.

“This is good news for the company, though it could be overshadowed if U.S. safety regulators find a problem with the car’s design,” Kelley Blue Book senior analyst Karl Brauer wrote. “Most American consumers will wait until NHTSA completes its investigation before deciding how confident they are regarding the design of the Model S.”

An agency representative told this newspaper Tuesday that the investigation is “ongoing,” and said there was no specific timetable for completion. The agency posted its Nov. 27 letter to Tesla requesting information on the fires and the company’s investigations on its website Tuesday morning — standard practice, according to a Detroit News report; a full response is due by Jan. 14.

Jack Nerad, executive editor and analyst at Kelley Blue Book, reported Tuesday that NHTSA Administrator David Strickland told him in a recent interview that Tesla “was going well beyond the norm in providing information and access regarding the vehicle fire issues.”

Staff writer Dana Hull contributed to this report. Contact Jeremy C. Owens at 408-920-5876; follow him at Twitter.com/jowens510.