It appears that McLaren is working on a new and exclusive hypercar that is called the 620R. The 620R is a road-going version of the 570S GT4 racing car. The design is said to be linked to the 570S MSO X that was launched last year. The 620R has an aero package that appears to be adapted from the McLaren racing program.
The car will have a large rear spoiler and a front splitter that is meant for downforce. The car also has a roof-mounted air scoop and new air intakes in the hood. The exhaust feeds out through the rear bumper, not the top exits that the 600LT offers.
The wheels are a new design and are thought to be made from magnesium. The assumption is that the car will have a unique suspension, but that is unclear at this time. More details should land in the future, like power numbers and availability.