It's hard enough to be a start-up these days, let alone an alternative-car company. Just ask electric vehicle producer Tesla Motors, which until now has basked in the glow cast by its founder, technology Midas Elon Musk.

But Tesla, a public company based in Palo Alto, was the latest alternative energy company to stumble, when it announced in a September 25 Securities and Exchange Commission filing that it had significant cash-flow issues that jeopardize conditions of an important federal loan. In a separate filing on Sept. 28, Tesla said it would issue an additional seven million shares to make up for the shortfall.

Tesla shares were $29.39 in late afternoon trading on September 28, down from the stock's 52-week high of $39.95.

The situation is reminiscent of what happened to Fisker Automotive, an electric-vehicle company based in Anaheim, California, which earned scathing comparisons to the now-defunct solar panel company Solyndra from the Romney camp this summer during one of its campaign stops. Solyndra went bankrupt in 2011 owing more than $500 million to taxpayers from another Department of Energy loan program.

Like Tesla, Fisker had violated covenants of its Advanced Technology Vehicles Manufacturing Loan program financing by missing production deadlines. The company consequently became a Republican boogeyman of government waste and cronyism this summer.

Under the program, Tesla was eligible for $465 million in 2010. Fisker was approved for a $529 million loan in 2009. Tesla drew down its entire loan, while Fisker drew down about $200 million.

Tesla negotiated sweeter terms for its loan covenants, though. Whereas the DOE froze Fisker's loan indefinitely in 2011 until it could work out a new production schedule, Tesla negotiated a temporary suspension of its current financial ratio requirements in September for the third quarter and postponed half of a prepaid financing payment until February 2013, among other things, in return for an accelerated repayment plan.

"It is pretty common with new technology and the new entrants to the business, such as Tesla and Fisker, that they are often overly optimistic--and they overestimate how difficult the auto industry is," says Mike Omotoso, an industry analyst with LMC Automotive in Troy, Michigan.

Certainly it costs a lot of money to launch a new car business. In fact, it costs hundreds of millions of dollars. 

New companies need that money for research and development, for production, to be properly licensed, to pursue distribution and marketing, as well as to tackle regulations and consumer safety, says Tim Lipman, co-director of the Transportation Sustainability Research Center, at the University of California, Berkeley.

And the cash crunch for Fisker and Tesla has made it difficult for them to make headway in the complex auto market. Both companies currently manufacture cars with price tags of $100,000, which put them out of reach for most consumers. (Both companies are also developing less expensive vehicles that could ultimately tap into a broader base of consumers.)

To do so, Fisker has sold off large parts of the company to raise $1 billion of equity investment, since it only drew down a portion of the loan. In contrast, Tesla used up its entire loan and now has to tap public markets to raise more cash.

By all accounts Fisker is feverishly trying to raise more money from private investors while it attempts to unfreeze its DOE financing to build out a manufacturing plant in Delaware and continue work on its less expensive Atlantic sedan. Similarly, Tesla needs cash to continue research and development and to complete its more affordable S and X lines of cars. The S started limited retail deliveries in June, and the X has yet to materialize, but both cars have $133 million worth of preorders, according to Tesla.

"These companies are trying not to be dependent on federal money; they want to be privately capitalized," says Lipman.

Still, their financial struggles are compounded by a tepid market for alternative-fuel vehicles, as well as by increased competition from more established automotive players.

"Most of our current and potential competitors have significantly greater financial, technical, manufacturing, marketing and other resources than we do and may be able to devote greater resources to the design, development, manufacturing, distribution, promotion, sale and support of their products," Tesla said in its 8-K, an SEC form used to inform investors of material events.

Since 2008, Tesla has sold about 1,500 Roadsters according to LMV Automotive. Fisker says it has sold about 1,500 Karmas since December. Similarly, Mitsubishi's iMiEV has sold fewer than 400 units of its all-electric vehicle, and Ford has only sold about 200 of its electric Focus cars in 2012.

Even more mainstream electric and hybrid vehicles have not sold particularly well recently. The Nissan Leaf, which is electric, and the Chevy Volt, which is hybrid, both retail for around $30,000. In 2011, both companies sold fewer than 10,000 units of these cars, below company forecasts. By comparison, the Chevy Malibu, a standard gas-powered car, sold more than 200,000 units in 2011.

"That's not a good sign in an [automobile] market that grew by 10%" over the same period, Omotoso says. 

This story was updated on October 1, 2012 to correct the total number of Fisker Karmas sold.