Toyota’s US sales fell by more than a fifth last month, allowing General Motors to retain its decades-long dominance of the world’s biggest car market.

GM’s sales fell by a more modest 18 per cent, helped by a generous interest-free financing promotion that it put in place last week to spur demand. GM sold 69,000 more cars and light trucks than Toyota last month compared with a gap of fewer than 10,000 in May.