Tesla has reported its lowest profit margin in five years. The car maker has been forced to cut prices in recent months to compete with rivals. "Overall, our focus remains on company-wide cost reduction," the company said on Tuesday in an update for investors. Elon Musk, the company's CEO, said he would be shocked if his self-driving cars weren't ready to operate without human supervision on US roads by the end of next year. Subscribe here: http://bit.ly/1rbfUog For more news, analysis and features visit: www.bbc.com/news #Tesla #ElectricCars #BBCNews