Renault had to reconsider its strategy after losing to Lancia in the World Rally Championship. So it launched a particularly daring project: transforming the economical R5 supermini into a genuine podium-capable racing car.
The project was ordered by Jean Terramorsi, Renault's VP for production cars, based on the existing model 5. Marc Deschamps from Bertone design studio came up with the idea of installing the engine behind the seats. Thus the idea of a mid-engine race car was born. After trials and errors, it came with the prototype in 1978. Due to the FIA's regulations, Renault chose the Alpine's 1.4-liter powerplant, which was mated with a five-speed manual gearbox carried over from Renault 30.
Moreover, thanks to extensive modifications and the addition of a turbocharger and a K-Jetronic fuel-injected system, the result was a 157 hp (160 PS) powerplant that sent the torque to the rear wheels. Unlike the standard 5, which featured a torsion-beam suspension system, the 5 Turbo used a multi-link system carried over from the Alpine A110.
These modifications were placed into a car styled by Marcello Ghandini from Bertone. Apart from the front fascia that was enhanced with a fat bumper, the most significant change was behind the B-pillars. There, the wider quarter panels featured air intakes for cooling the engine and feeding the turbocharger's intercooler.
Inside, Renault installed a pair of sports seats with high-bolstered areas and four-point seatbelts. Last but not least, the dashboard was upgraded to accommodate more gauges for the boost pressure, oil temperature, and other info required by a race car.
The final version came on the market in 1980. Thanks to its under seven-second 0-62 mph (0-100 kph) run and the top speed above 125 mph (200 kph), the Renault 5 Turbo became the fastest French car of its era.