The car's styling group was led by Ian Callum of Tom Walkinshaw Racing (TWR). The mechanical and aerodynamic design was led both by Tony Southgate, also of Tom Walkinshaw Racing (TWR), and Mr. Yutaka Hagiwara of Nismo. Southgate was the designer of the Jaguar XJR-9 amongst other TWR sports cars, which had won at Le Mans. Due to this, the R390 GT1 bears a resemblance to the Jaguar XJR-15, which was also developed by TWR and based on the XJR-9, and in fact used a cockpit - including the tub, greenhouse and roof line - from the very same tooling as the XJR-15, with some custom tooling blocks added to the XJR15 chassis mold, although for the R390, the rear and front ends, and suspension were completely different and were designed to meet GT1 specifications, the R390's chassis was lower and wider, but slightly shorter in length than the Jaguar, making the R390 larger overall. Development of the car was achieved in a small amount of time, especially due to the use of an existing engine. Nismo and TWR also had to build a road legal version of the R390 GT1 in order to meet homologation requirements. A red R390 prototype underwent wind tunnel testing and aerodynamic improvements in England, however, the final car was built and tested in Atsugi, Japan. Only one road legal R390 was built, which is currently in storage at Nissan's Zama, Kanagawa facility.