Volvo's Self-Driving Cars Confused by Kangaroos in Australia Volvo's self-driving cars use the ground as a reference point for distance, and the kangaroo's hopping makes it hard to determine how far away they are.

If staying inside the lines while steering clear of pedestrians and other vehicles isn't enough, self-driving cars in Australia have to contend with another particularly challenging obstacle: kangaroos.

Volvo has been testing it autonomous vehicles in Australia, and working to solve the roo issue, according to a report from the Australian Broadcasting Corporation. Volvo Australia's Technical Manager David Pickett told the ABC that the unusual way the marsupials move confuses the company's autonomous vehicles. The problem is that Volvo's self-driving cars use the ground as a reference point for distance, and the kangaroo's hopping makes it hard to determine how far away they are.

"When it's in the air it actually looks like it's further away, then it lands and it looks closer," Pickett said, according to the report.

Volvo has already tested its detection system on other large animals, such as moose in Sweden, with more success. The company's research team has spent the past 18 months at Tidbinbilla Nature Reserve in Australia studying kangaroos, but they're still working to nail down a solution.

Just getting the car to recognize roos has been a struggle.

"If you look at a roo sitting at the side of a road, standing at the side of a road, in motion, all these shapes are actually different," Pickett said.

The company is confident it can solve the problem, and says the issue won't delay the rollout of autonomous vehicles in Australia, according to the report.

Kangaroos cause more car accidents in Australia than all other animals combined, Melbourne-based newspaper Herald Sun reported last year. The hopping herbivores are reportedly responsible for around 90 percent of road accidents involving animals nationwide.