The Detroit 3 carmakers, GM, Chrysler and Ford are teetering on the edge of 50% market share and could slip below the milestone mark by as early as this month. For the end of June, the trio commanded just 50.2% of the US domestic market, down from 56% the year before and a new all time low for the struggling carmakers.

Most of the competition is coming from Japanese brands, which have moved up to a 37.5% share last month and show no sings of slowing with heavy discounting continuing on even the popular models, reports Automotive News.

Now the question is whether or not the Detroit 3 should increase incentives on its own models to help turnaround flagging sales. Unfortunately, most experts agree this will have no effect except to slow it down, in fact, "the chances of it happening next month are better than 70%," says Art Spinella, head of CNW Marketing Research.

In recent months Ford and GM have been reducing incentives and cutting back on fleet sales to improve profit levels but execs didn’t anticipate the weak housing market and unfavourable exchange rates which has since seen sales plummet.