Ford sold just 717 Falcons last month and the 53-year-old nameplate is in danger of falling below the 10,000 mark for 2013 on its current selling rate, which is reflected by a year-on-year decline of 28 per cent.
Toyota's Aurion managed only 469 units in April, bringing its total for the year so far to 1564 and a 30 per cent drop on April 2012.
The Holden Commodore has the biggest year-on-year decrease - 39 per cent - after 1515 units were moved last month, though the model is in run-out mode as the company prepares to launch the new Holden VF Commodore (above) in early June.
New imported rivals are on the horizon, however, with a new-generation Honda Accord launching officially next week, and the new Nissan Altima due later this year.
Sales of locally manufactured vehicles are down 26 per cent compared with April 2012 - from 43,905 to 32,573 units.
The Holden Cruze had a strong April, however, with 2290 sales cementing its position as the best-selling homegrown car, while Ford will be encouraged by its Territory SUV that found 1260 owners last month that contributed to a four per cent year-on-year growth.
Toyota's Camry also performed solidly in April with 1617 sales, though the medium car is down 18 per cent year on year.