The shaky economy has taken a toll on one of the hottest startups in Silicon Valley, where Tesla Motors chairman and chief investor Elon Musk has taken over as CEO, laid off employees and delayed production of the company's promised electric sedan in a scramble to save cash. The shakeup is "a strategic response to the liquidity crunch" that will see the electric car company downsize its operation and "focus on our two revenue-producing business lines" — producing the battery-powered Roadster sports car and selling electric drivetrains to other automakers, Musk wrote on the company's blog. "Our goal as a company is to be cash-flow-positive within six to nine months," wrote Musk, who has invested some $55 million in the company. "To do so, we must continue to ramp up our production rate, improve Roadster contribution margin and reduce operating expenses."