Base Game Cars
Rally  Historic Rally H1 (FWD) (3/3): 

Citroen DS 21 (Confirmed here)
Lancia Fulvia (Confirmed here)
Mini Cooper (Confirmed here)

Historic Rally H2 (FWD) (2/2):

Peugeot 205 GTI (Confirmed here)
Volkswagen Mk.2 Golf GTI (Confirmed here)

Historic Rally H2 (RWD) (4/4):

Fiat 131 Abarth (Confirmed here)
Ford Mk.2 Escort (Confirmed here)
Opel Kadett C GT/E (Confirmed here)
Renault Alpine A110 (Confirmed here)

Historic Rally H3 (RWD) (6/6): 
BMW E30 M3 (Confirmed here)
Datsun 240Z (Confirmed here)
Ford Sierra RS Cosworth (Confirmed here)
Lancia Stratos (Confirmed here)
Opel Ascona 400 (Confirmed here)
Renault 5 Turbo (Confirmed here) 

Historic Rally Group B (4WD) (5/5):

Audi Sport quattro E2 (Confirmed here)
Ford RS200 (Confirmed here)
Lancia Delta S4 (Confirmed here)
MG Metro 6R4 (Confirmed here)
Peugeot 205 T16 Evo 2 (Confirmed here)

Modern Rally Group A (4/4):

Ford Escort RS Cosworth (Confirmed here)
Lancia Delta Integrale (Confirmed here)
Subaru Impreza WRX STi (Confirmed here)
Mitsubishi Lancer Evolution VI (Confirmed here)
Modern Rally GT (5/5):

Aston Martin V8 Vantage GT4 (Confirmed here)
BMW M2 Competition (World Championship participation reward) (Confirmed here)
Chevrolet Camaro GTR.4 (Confirmed here)
Ford Mustang GT4 (Confirmed here)
Porsche (997) 911 RGT (pre-order bonus) (Confirmed here)

Modern Rally R2 (3/3):

Ford Fiesta R2 (Confirmed here)
Opel Adam R2 (Confirmed here)
Peugeot 208 R2 (Confirmed here)

Modern Rally NR4/R4 (2/2):

Mitsubishi Lancer Evolution X (Confirmed here)
Subaru WRX STI NR4 (Confirmed here)

Modern Rally R5 (6/6):

Citroen C3 R5 (Confirmed here)
Ford Fiesta R5 (Confirmed here)
Mitsubishi Space Star R5 (Confirmed here)
Peugeot 208 T16 R5 (Confirmed here) 
Skoda Fabia R5 (Confirmed here)
Volkswagen Polo GTI R5 (Confirmed here)
  Rallycross
Supercars (7/7):

Audi S1 4x4 T16 (Confirmed here)
Ford Mk. 7 Fiesta 4x4 T16 (Confirmed here)
Ford Mk. 8 Fiesta 4x4 T16 (Confirmed here)
Peugeot 208 4x4 T16 (Confirmed here)
Renault Megane RS RX 4x4 T16 (Confirmed here)
Subaru WRX STI (Confirmed here)
Volkswagen Polo R 4x4 T16 (Confirmed here)

RX Lites (1/1):
OMSE RX Lite (Confirmed here)
Super 1600 (3/3):

Opel Corsa S1600 (Confirmed here)
Renault Clio S1600 (Confirmed here)
Volkswagen Polo S1600 (Confirmed here)

Crosskarts (1/1):

Speedcar Xtrem (Confirmed here)   Confirmed Rally Cars (Base Game): 38 (39 with pre-order, 40 following World Championship participation) Confirmed Rallycross Cars(Base Game): 12
Total Confirmed Car (Base Game): 50 (51 with pre-order, 52 following World Championship participation)   DLC Cars Modern Rally Group A (1/1): 

Subaru Legacy RS (Flat Out Pack)(Confirmed here)

Modern Rally 2000cc (8/8):

2010 Citroen C4 Rally (DLC1)(Confirmed here)
2001 Ford Focus WRC (DLC3)(Confirmed here)
2007 Ford Focus RS Rally (DLC1)(Confirmed here)
Peugeot 206 WRC (DLC3)(Confirmed here)
2005 Skoda Fabia Rally (DLC1)(Confirmed here)
1998 Subaru Impreza S4 (Flat Out Pack)(Confirmed here)
2001 Subaru Impreza (DLC3)(Confirmed here)
2008 Subaru Impreza (DLC1)(Confirmed here)

Historic Rally Group B (RWD) (4/4): 

BMW M1 Procar (DLC1)(Confirmed here)
Lancia 037 Evo 2 (DLC2)(Confirmed here)
Opel Manta 400 (DLC1)(Confirmed here)
Porsche 911 SC RS (DLC2)(Confirmed here)

Kit Car (3/3): 

Peugeot 306 Maxi (DLC3)(Confirmed here)
Seat Ibiza (DLC3)(Confirmed here)
Volkswagen Golf (DLC3)(Confirmed here) Group B Rallycross (4/4):

Ford RS200 Evolution (DLC2)(Confirmed here)
Lancia Delta S4 (DLC2)(Confirmed here)
MG Metro 6R4 (DLC2)(Confirmed here)
Peugeot 205 T16 (DLC2)(Confirmed here) Supercars (2019) (9/9):

2019 Audi S1 4x4 T16 (DLC4)(Confirmed here)
2019 Ford Mk. 8 Fiesta 4x4 T16 (DLC4)(Confirmed here)
2019 Ford Fiesta (STARD) 4x4 T16 (DLC4)(Confirmed here)
2019 Ford Fiesta RXS Evo 5 4x4 T16 (DLC4)(Confirmed here)
2019 MINI Cooper S 4x4 T16 (DLC4)(Confirmed here)
2019 Peugeot 208 4x4 T16 (DLC4)(Confirmed here)
2019 Renault Clio RS RX 4x4 T16 (DLC4)(Confirmed here)
2019 Renault Megane RS RX 4x4 T16 (DLC4)(Confirmed here)
2019 Seat Ibiza 4x4 T16 (DLC4)(Confirmed here) Confirmed DLC Rally Cars:  16 Confirmed DLC Rallycross Cars: 13
Total Confirmed Car (Base Game, DLC1, DLC2, DLC3, DLC4 & Flat Out Pack) 79 (80 with pre-order, 81 following World Championship participation)