The interior of the 849 Testarossa Spider is a synthesis between the layout of a berlinetta with a horizontal dashboard and the cockpit of a single-seater. The interior design instead sets out to optimize space and improve ergonomics.

Developed by the Ferrari Styling Centre, the 849 Testarossa revolutionizes the shape of the SF90 Stradale and emphasizes the car's technological performance. The 849 Testarossa Spider incorporates all the experience Ferrari has gained with retractable hardtop (RHT) technology. With the roof closed, the car maintains the volumes of the 849 Testarossa; when open, the rear section stands out for its iconic and powerful forms. In the 849 Testarossa Spider the double-tail architecture becomes the absolute star, making the overall design unique.

The 849 Testarossa Spider is equipped with a plug-in hybrid (PHEV) system consisting of the 830 cv twin-turbo V8 engine combined with three electric motors, a high-voltage battery, and an inverter that together deliver a total output of 220 cv. This system brings the total power of the powertrain up to 1050 cv, an absolute record for a production Ferrari. The architecture of the 849 Testarossa Spider's plug-in hybrid powertrain has been designed to ensure maximum performance, vehicle dynamics, and usability.