Wishing to expand on the R382's winning formula even further, the R383 borrowed heavily from Can-Am cars running the Group 7 formula in North America.

The venting on the nose of the R382 was removed, leaving the entire frontal area of the R383 flattened.

The air intake for the V12 engine was also aerodynamically redesigned, now being placed below the rollbar in order to allow more air to the rear wing, as well as slightly off center of the cockpit in order to avoid the driver's helmet blocking the intake.

The R383 was also tested with a turbocharger added to the V12 engine, allowing for an increase of output to 900 hp.

[4] The R383s were planned to be entered at the 1970 Japanese Grand Prix, against heavy competition from Porsche, Toyota, Isuzu, and others.