The choice was inevitable: if the successor to the all-conquering Lancia 037 was to have any chance of winning the World Rally Championship, it required four-wheel drive. In order to test the principles of this emerging technology, Giorgio Pianta spent one month creating a bizarre twin-engined prototype: the Lancia Trevi Bimotore.
In 1984 Lancia needed to replace the Rally 037. The rear-wheel-drive car had already performed miracles by winning the World Rally Championship for Makes the previous year, beating emerging Audi and Peugeot cars equipped with all-wheel drive; however, the clear technical superiority of its rivals convinced Lancia to develop a new contender with all-wheel drive.
In the Chivasso plant, Giorgio Pianta (versatile racing driver, test driver and Abarth team manager) designed and built a car that used two engines to provide four-wheel drive. The point of departure was the new Lancia Trevi Volumex, equipped with a supercharged two-litre engine that provided the vital low-end torque needed to win rallies.
Pianta dispensed with the rear seat bench, leaving a gap at the rear of the bodyshell for a subframe (just like the one at the front) that would house a second engine, identical to the first. The entire front axle, engine, gearbox and suspension were effectively duplicated at the rear. The rear doors were welded shut and fitted with large air intakes that cooled the mid-mounted engine. The deflector on the rear upright was also opened to provide another air inlet.
Although the red livery and the longitudinal stripe in the colours of Turin bring to mind the Amaranto Montebello colour of the winning Fulvia HF, the Trevi Bimotore definitely lacked sportiness and a competitive streak. Nevertheless, it proved to be an effective test vehicle.
The two engines were not mechanically coupled, only the two gearboxes were connected so that they could be operated by a single lever, with just one pedal to activate the two clutches. The two accelerators were controlled by a rudimentary electronic system that determined the delay in supplying power to the rear axle. In this way, Pianta tried to reduce oversteer and achieve faster curve exits to get the most out of his original creation.
The dashboard had two rev counters, the second of which replaced the speedometer, and two central gauges indicated the water temperature and oil pressure of each engine. The space-age dashboard was based on the standard design by Mario Bellini, with some indicator lights modified so that both engines could be kept under control. Although the car was fast and very effective, it was overweight due to having twice the mechanicals and the rear engine had a tendency to overheat.
The solution was not adopted on the Lancia Rally’s successor, the Delta S4, but curiously some similarities can be found in the road version of the S4: they include a mid-mounted engine, enclosed in a casing covered by the same beige carpet used in the passenger compartment, which was the exact same solution adopted by Pianta in the Trevi Bimotore. Other similarities: the removable wheel rims were identical to those on the road-going S4, because the Trevi Bimotore was used to test the special Pirelli tyres produced specifically for the new Lancia.