Landon Kupfer thought he’d grabbed a piece of the Silicon Valley dream when Tesla Inc. hired him about a year ago to work on quality issues at the company’s Fremont, Calif., factory.

The perks included driving Tesla cars and impressing friends and strangers curious about work at one of the tech industry’s hottest brands. “Getting a job there was pretty exciting,” said the 23-year-old San Jose native, who had experience fixing cars and installing windows but thought a job at the tech giant was beyond his reach.

His excitement was soon met with the complexities of mass-production during a remarkable period in Tesla’s history, as it ramped up production of its electric car for the mainstream, the Model 3 sedan. Mr. Kupfer’s team stretched to reach tougher manufacturing targets each week. “We’d get one goal to work toward, we’d hit that goal, then, Boom!—it didn’t even matter—let’s go to the next thing,” said Mr. Kupfer, who left the Bay Area after a few months to relocate to Texas, where he said the cost of living is better.

For many young engineers and other job seekers eager to advance environmentally-friendly vehicles and create something new, landing a job at the Palo Alto auto maker can be a hard-to-pass-up career break.

After they arrive, many say they learn it also means long hours and a frenzied pace. For some, it can soon lead to exhaustion or the temptation to accept offers from tech firms eager to hire talent with Tesla experience.