Tesla is beginning deliveries of its Semi trucks to a first set of customers this week, executives said at its plant in Sparks, Nevada, almost nine years after CEO Elon Musk unveiled the electric big rigs. The Semi, designed for long-haul freight, expands the market for Tesla, known for its electric sedans and SUVs, into commercial freight haulers at a time when diesel prices in the US have soared to record highs. Tesla did not disclose production volume plans or pricing of the trucks at a webcast event late on Thursday at the plant. It reiterated plans to build 50,000 Semis a year at the Nevada plant. Musk did not attend the event. In a recorded video message he said: "I'd recommend placing more orders if you haven't already, but the waiting list is already pretty significant."