The technology to allow a driverless vehicle to move fully autonomously is not ready yet, according to a leading autonomous vehicle company.

Mr Karl Iagnemma, chief executive of Motional - a newly rebranded joint venture between Hyundai Motor and Aptiv (previously known as Nutonomy) - said in a webinar on Wednesday that his company will focus on Level 4 autonomous driving, which is a notch below the fully autonomous Level 5.

"Level 5 technology refers to a vehicle that can perform all the driving tasks under any circumstances, which you might call anytime, anywhere," Mr Iagnemma said in response to a question from The Straits Times.

"I would argue that human drivers are today not Level 5 drivers. We tend to pull over if the conditions get too hazardous, if the rain is too intense, if the snow is too heavy, for example."

He said Motional is focused on developing Level 4 autonomous driving, which is driverless movement within certain geofenced or well-defined environments.

"Today, it's beyond the state-of-the-art and driverless technology to develop Level 5," he added. "This is not to say it will never happen. But today, a more realistic goal is to focus on Level 4."

Level 4 autonomous driving typically requires a set of conditions, including well-marked road lanes, relatively fair weather and, often, the installation of special roadside systems such as sensors.

In Las Vegas, for instance, where Motional had undertaken 100,000 rides with its "robotaxis", sensors help its cars navigate signalised junctions.

Motional was unable to say how much such infrastructural systems would cost to implement, but Mr Iagnemma emphasised that "our philosophy is that we should adapt our technology to the existing infrastructure, rather than require the infrastructure to be adapted to our vehicles".

"I know that if we have to rely on a third party to accomplish a difficult, expensive and time-consuming task, it makes our path to market increasingly risky.

"With that said, I would make one distinction: If there is the ability to instrument the environment with simple sensors that will help our vehicles, we'll take advantage of it."

But he added that Motional's systems can "operate effectively without any customised infrastructure".

Motional did not say when it will roll out "robotaxis" in Singapore, but the company had previously said its "robotaxi" technology will be ready by 2022.

In Singapore, the company has hired "more than 25 full-time employees" from the time the joint venture with Hyundai was formed in March, and Mr Iagnemma expects to add "more than 30 jobs" before year-end.

The staff strength in Singapore now is about 200.

The company in its previous form conducted self-driving trials in Singapore from early 2016.

On Oct 18 that year, one of Nutonomy's cars, which had two safety engineers on board, collided with a lorry in Biopolis Drive in what is believed to be the first accident in Singapore involving an autonomous vehicle.

The company said software glitches were responsible.

Singapore has had several autonomous vehicle trials since 2014, but mostly in low-traffic environments such as university campuses and parks.

Last year, the Government said such trials will take place on public roads in the western part of the island soon.

In this year's Budget, it said some $6 million has been set aside for the test-bedding of autonomous vehicles.