Defending champions Nuon are leading the 2017 race of solar-powered cars from Darwin to Adelaide.
By mid-afternoon on Monday, the Dutch car was about 950km south of Darwin after Sunday's start to the 3000km World Solar Challenge.
The team from Tokai University were just 2km behind and the two cars were well ahead of their nearest rivals.
Third place appeared to be a battle between another team from the Netherlands, Solar Team Twente, and the entry from the University of Michigan.
The leading Australian car, the Western Sydney Solar Team, was holding down fifth spot on Monday after covering about 904km.
If the Dutch lead the way into Adelaide it will be their seventh victory in the event that they have come to dominate in recent years.
In this year's race, teams from more than 20 countries are taking part, including entrants from Iran, Belgium, Chile and the US.
The leading cars are expected to reach Adelaide on Thursday.
This year's race marks 30 years since the first World Solar Challenge in 1987.
