Group B was launched in 1982 with the purpose of attracting more makes into the World Rally Championship, by reducing from 400 to 200 cars per year the minimum production requirement, and requiring only an additional 10% to introduce new homologations.
M. Biasion/T.Siviero, Lancia Rally 037, Rally of Portugal, 1984, 4th.
First real group B was Lancia Rally 037, the last victorious rally car based on two-wheel drive. Designed by Sergio Limone and after many tests in the Pininfarina wind tunnel, the car (on its rally version) was dotted with a huge rear spoiler, which gave the car an incredible amount of aerodynamic load, needed to maintain the back wheels stuck to the road. After some wind tunnel studies, they opted for a major negative lift to the detriment of some fewer kilometers at top speed. Since they had already chosen to mount an engine favoring the torque at low rates, it was obvious that aerodynamics should also have favored the drive features.
Final car design had a Cx = 0.55, which was going to be soon improved by future competitors. See Homologation Form here.
Audi soon homologated his group 4 Quattro model as group B in early 1983 (see Homologation Form here), so new modifications could be more easily introduced. The rear spoiler was replaced by a wing, bigger size, in the new car (named A1 version).
H. Mikkola/A.Hertz, Audi Quattro A1, Monte Carlo Rally 1983, 4th.
Only a few months later (may 1983), Audi homologated (see Homologation Form here) a lighter version (A2) but with the same rear wing. This car dominated the 1984 Championship, but the presentation of the new Peugeot 205 T16 model supposed the starting point of an aerodynamic revolution in rally cars.
S. Blomqvist/A. Cederberg, Audi Quattro A2, New Zealand Rally 1984, 1st.
W. Röhrl/C. Geistdörfer, Audi Quattro A2, Monte Carlo Rally 1984, 1st.
A vertical radiator was installed below the rear wing in order to force air to flow upwards, thus generating higher load but also higher drag, while also improving car weight load distribution.
The same aerodynamic solution was used in the shorter Audi Quattro Sport car, which was first used in 1984 Rally Cote d’Ivoire, and during most of 1985, until it was replaced by the impressive Audi Quattro E2.
W. Röhrl/C. Geistdörfer, Audi Quattro Sport, Monte Carlo Rally 1985, 2ond.
But then, the Peugeot 205 T16 changed it all.