US carmakers General Motors and Ford are slashing production volumes and ramping up incentives even further after Far Eastern rivals took another big slice out of their home market last month.
Of the Detroit two it was GM that suffered most in May as sales of its cars and trucks slumped by 12.8 per cent.
It may still be the world's biggest automotive firm but it is in danger of being overtaken by Toyota, which leapfrogged Ford into the number two spot a long time ago.
And it is Toyota that is helping to spearhead the Far Eastern advance on a US market in which the Detroit "Big Three" - GM, Ford and Chrysler - were once regarded as invincible.
Its sales rose by 7.8 per cent last month in a truck and car market that declined by eight per cent to an annualised total of 16.7 million compared with last May's more robust 17.7 million.
Toyota, Nissan and Honda now not only build the five bestselling cars in the world, they also control more than 32 per cent of the US market.
Throw in the South Koreans - Hyundai and Kia - and the combined Far Eastern share of the market grows to 36.4 per cent.
Detroit, which once made in the order of eight out of every ten cars and trucks sold in the US, has seen its market share shrink to under 58 per cent.
Ford, which owns Jaguar and Land Rover as part of its Premier Automotive Group portfolio of luxury brands, suffered a 10.5 per cent sales drop last month and was 5.6 per cent down on the year so far.
It was the twelfth monthly slump in a row for Ford and the company faces further embarrassment after a conservative Christian group in the US launched a boycott of its vehicles, claiming the group was actively recruiting gay employees, offering benefits to same-sex couples and financially supporting gay rights groups.
Ford, whose targeted marketing tactics include offering to donate $1,000 to the Gay and Lesbian Alliance Against Defamation for every Jaguar and Land Rover its supporters buy, said it was only doing what other manufacturers do.
A spokesman in the US said: "Ford values all people, regardless of of their race, religion, gender, sexual orientation and cultural or physical differences."
Land Rover was Ford's star performer last month, gaining 20 per cent to 2,873 thanks to the success of the third generation Discovery (badged LR3 in the States) which was introduced last October and which so far this year has sold 8,306 units.
The Solihull manufacturer is 11 per cent ahead on the year so far and is set to gain even more sales on the back of the new Ranger Rover Sport which comes to market soon.
Against that, however, Land Rover is pulling the Freelander out of the US market as stocks of Freelander's petrol engine produced by the bankrupt MG Rover subsidiary Powertrain run out.
May was another bad month for Jaguar, whose sales have been damaged by the weakness of the dollar and the deep discounting of its rivals, with a further 39 per cent fall to 2,697 units.
Jaguar was rated second in quality only to Lexus, in the latest JD Power survey.