Tesla sales declined in the first three months of the year, another sign that Elon Musk's once high-flying electric car company is struggling to attract buyers.

The drop of 13 per cent is likely due to combination of factors, including its aging lineup, competition from rivals and a backlash from Musk's embrace of right wing politics. It also is a warning that the company's first-quarter earnings report later this month could disappoint investors.

Tesla reported deliveries of 336,681 globally in the January to March quarter. The figure was down from sales of 387,000 in the same period a year ago. The decline came despite deep discounts, zero financing and other incentives.

Analysts polled by FactSet expected much higher deliveries of 408,000.