A Model S leaving the Tesla Motors factory floor on Friday.Paul Sakuma/Associated PressA Model S leaving the Tesla Motors factory floor on Friday.

FREMONT, Calif. — On a Friday filled with press conferences, roundtable discussions, production-line walk-throughs and chaperoned test drives, it was only at a concluding pep rally, held on the Tesla Motors factory floor here, that the mood became palpable. As executives for the electric-vehicle start-up handed keys to the first Model S sedans to retail customers, the sense of a victory, to some an improbable one, came across as loud and giddy as any celebration of a basketball championship.

Wearing cherry-red polo shirts, Tesla employees whooped, whistled and hollered as executives recalled the journey to Tesla’s first retail-ready, baked-from-scratch electric car, starting with a meeting in 2008 in which Elon Musk, co-founder and chief executive of Tesla, presented “a laundry list of things that didn’t equal a sedan,” to his newly hired chief designer, Franz von Holzhausen.

It should seat seven people, have the best zero-to-60 time of any sedan on the road and be the “best-looking car in the world,” Mr. von Holzhausen recounted to the crowd.

By the rally’s conclusion, 10 vehicles had been released into the wild, most of them painted Signature Red. Mr. Musk and Steve Jurvetson, an early investor, received the first two earlier this month. Five cars were handed over to customers onstage on Friday. And two additional vehicles departed Tesla’s plant for delivery to buyers in Chicago. One Model S was to be taken just across the bay to Palo Alto.

Each car that rolled out of the factory — a former General Motors plant that had become a Toyota plant — had a glossy, 17-inch touchscreen control panel that resembled an enormous iPad. Fortunately, the screen has a night mode, which switches most of the bright whites to black, dimming the display enough to reduce the eye-magnet effect. In a move that may please Tesla’s Silicon Valley constituency but rile safety regulators, it is technically possible to use the built-in Internet browser while driving.

And the car manages to accommodate seven people, but just barely. The front seats are cushy but plenty supportive, and two passengers can sit comfortably in the second row (three adults, however, would be a squeeze). Two rear-facing child seats, which fold neatly into the floor, are tiny and cramped beneath the sloped roof.

Tesla recommends these seats for children up to age 10. Combined with increasingly stringent rules for child safety seating (California law, for example, requires children up to age 8 or a height of 4-foot-9 to ride in a booster seat), this suggests limited utility.

The sloping roof, designed to help minimize wind resistance, also hampered rearward visibility during a brief test drive on the roads and highways near the factory, leaving just a narrow slit of glass in which to view approaching traffic.

Nancy Pfund, a managing partner at D.B.L. Investors, an early Tesla backer and a former managing director for JPMorgan Chase, was one of the Model S customers presented with keys (electronic ones, of course) by Mr. Musk. On the sidelines of the event, she said the car would become her daily driver.

“I’ve been driving — keeping my fingers crossed that it wouldn’t break down — an old Mercedes,” Ms. Pfund said. She plans to retire the 2000 Mercedes-Benz and use the Model S for errands and her commute: 14 miles across the bay to San Francisco, and south to Silicon Valley, “about 100 miles round-trip,” she said. “They do have two charging stations at my office, so they’re all excited to have me come in on Monday.”

Of course, as any Tesla employee would argue, the Model S is not intended for such narrow use. The versions that went out on Friday were built with the Signature Performance package, and priced from just under $100,000 after applicable tax credits. This package comes with an 85 kilowatt-hour battery pack, rated by the Environmental Protection Agency for up to 265 miles of driving on a full charge.

According to JB Straubel, Tesla’s chief technology officer, the pack consists of more than 7,000 battery cells. Later this year, Tesla plans to begin offering versions of the Model S with smaller battery packs, including a 40 kilowatt-hour choice starting at $57,400 and a 60 kilowatt-hour pack starting at $67,400, excluding a maximum $7,500 federal tax credit.

Tesla’s executives expressed gratitude to the 2,300 buyers of the company’s first vehicle, the Roadster sports car — built on a chassis from Lotus — as well as to investors, the raucous crowd of employees and perhaps the most polemical honoree of all, the federal government, which provided Tesla with $465 million in loans through the Energy Department’s Advanced Technology Vehicles Manufacturing program.

“We hope to do really good by the Department of Energy, and show that the support was warranted, and there is a fundamental good that’s been achieved,” Mr. Musk said.

Gov. Jerry Brown made an unannounced appearance at the event. “California has its issues, but all of you are part of a state that is leading the country, if not the world, and this car is just another example of boldness,” he said.

“I certainly had nothing to do with this,” Mr. Brown added. “I love it when people spend their money and make great stuff.”

Under Arnold Schwarzenegger, Mr. Brown’s predecessor, the state approved $28.8 million in tax breaks for Tesla in 2009 in an effort to keep the company in California.

“Hopefully these cars will keep coming,” Mr. Brown said. “By the millions!”

Tesla vehicles, he added, might even make their way into the state fleet, “as we get a little more money and the price comes down.”

By JOSIE GARTHWAITE