Telsa's profits or losses per car have "vacillated wildly over the second quarter over the last couple of years," Greenhaus said. In the second quarter of 2013, the automaker made a profit per car of $1,941, and in 2014 it was even higher at a profit of $2,111 in 2014.
The latest figures from Q2 of 2015 show that Tesla loses exactly $4,144 per car.
Musk has taken investors on a thrill ride since taking Tesla public in 2010. Now he's given himself a deadline, promising that by the first quarter of 2016 Tesla will be making enough money to fund a jump from making one expensive, low volume car to mass producing multiple models, and expanding a venture to manufacture electric power storage systems.
Tesla's shares fell almost 9 percent on Thursday and slipped another 2 percent on Friday as investors and analysts weighed the risks of Musk's ambitious plans for expanding Tesla's auto and energy storage businesses.
Tesla had just $1.15 billion on hand as of June 30, down from $2.67 billion a year earlier.
Automakers consume cash to pay for assembly line equipment, including metal dies and plastic molds, as well as testing to meet safety and emissions standards. A typical new car can cost $1 billion or more to engineer and bring to market.
Established automakers such as General Motors and Ford Motor have amassed far larger cash cushions as they've rebuilt balance sheets battered by the 2008-09 recession. GM, restructured six years ago in a government funded bankruptcy, has targeted cash reserves of $20 billion and had more than $28 billion in cash equivalents as of June 30.
To be sure, GM sells more than 9 million vehicles a year, while Tesla plans to build between 50,000 and 55,000 cars this year. Tesla, most of whose cars are built to order directly, delivered 11,532 cars in the second period and said it had an operating loss of about $47 million, for an operating loss per car of about $4,000.
Tesla's narrower margin for error is just one more way in which it is different from its century old rivals.
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The company said it plans $1.5 billion in capital spending this year, mainly to launch its Model X, battery powered sport utility vehicle with eye-catching, vertical-opening "falcon wing" doors. Tesla reported $831 million in capital spending during the first half of the year, indicating it will spend roughly another $700 million.
During the second quarter, Tesla said operating costs and research and development spending rose, while average selling prices for the Model S lineup, which starts at $70,000 before federal and state electric vehicle tax breaks, fell 1 percent as the mix of sales shifted to less expensive models and a strong dollar hit revenue generated overseas. The Model S comes in several different versions, ranging in price up to $106,000 or more, depending on options.
Tesla has signaled capital spending will drop next year because the company won't be spending on a major vehicle launch. In 2017, Tesla plans to launch its Model 3 line, which the company says will start at about $35,000 and push total sales toward the goal of 500,000 vehicles a year by 2020.
But Greenhaus disagreed with Tesla's projections.
"[Tesla is] going to be burning through cash for the next few quarters, the next couple of years—and that's what worries people," Greenhaus said.
"But there's no other way to grow an automaker," he added. "You have got to invest in the infrastructure and that's what's going on with Tesla right now."
Barclays analyst Brian Johnson disagreed with the company's estimates, and said he expects Tesla's capital spending will go up in 2016 and 2017 as the company ramps up its battery factory and Model 3 development. "Their small scale means the cash generation is not as great as they might have hoped for," he said.
Musk said this week Tesla expects to have $1 billion in cash over the next year, and told analysts "there may be some value" in raising capital "as a risk reduction measure."
Tesla's stock is still about 70 percent higher than it was two years ago, and 8 percent ahead of its level on Jan 1. With a market capitalization of $31 billion, Tesla is worth more than Fiat Chrysler Automobiles, the much larger maker of Ram pickups and Jeep Grand Cherokees.