Musk: Tesla had to offer an affordable car to have impact

Tesla has unveiled the Model 3 - it's lowest-cost electric car to date.

The loss-making firm aims to have manufactured half a million vehicles by 2020, and believes the new automobile will make it possible to hit that target.

Earlier this year, the firm's chief Elon Musk told the BBC's Rory Cellan-Jones why Tesla had to make an "affordable" car.