I think it's now safe to add the seven DLC cars:
1. Koenigsegg One: 1 '14 (2015 in-game)
2. Mercedes-AMG C63 S Coupe '16
3. Chevrolet #30 Douglas Shierson Racing Lola T90/00
4. Ferrari 250LM '63
5. Holden VL Commodore Group A SV '88
6. Mazda #62 Mazda Motorsport RX-7 FC3S '91
7. Plymouth Fury '58
Also, this is supposed to be December's free car:
Nissan Silvia CSP311 '66
However, the car was silently added into the game, costing Cr. 72,000 and can only be bought when in "Stories of Motorsport" on the first volume under "Classic Sport Compact" and cannot be found in "Find a Car" or Free Play mode. It is fully functional like every other car, doesn't crash the game or corrupt anything and is accurately modeled when all the upgrades are reset (it comes with some parts when you buy it there).