After a record-breaking quarter, Elon Musk has told investors he has never felt more optimistic about the future of Tesla and predicted all transport will go autonomous in the long term.

The electric vehicle (EV) maker posted its fifth consecutive profitable quarter with free cashflow, defined as operating cashflow minus capex, of $US1.4 billion ($2 billion). Operating margins climbed to 9.2 per cent, versus 4.1 per cent in the prior corresponding quarter.