It's not possible. Such a car isn't in the game. All the $10m, $15m, $20m cars are unsellable. Be happy with your F10 and being able to potentially set the quickest lap time on almost every circuit whether it's competitive or not.
If your actually looking to trade, then Ill trade you The Nissan R92, The Minolta Racecar, and the Toyota 7 Racecar. That's about 4 million I believe. All brand new is worth much more than the formula car