the mitsubishi Lancer 'Evo'lution is only obtained right at the end of the game, in the last territory in career mode. it's a tier 3 car so use the RX7 for now until you can get it.
Here's a more detailed, yet simple guide to get the Mistubishi Lancer:
1. Beat all areas to unlock Silverton.
2. Beat a couple of races (and maybe a get a territory)
3. Eventually, there will be a territory. It'll have a race to unlock the Mistubishi Lancer (it's a canyon duel against that cheap-ass Kenji).
Now go get that Mistubishi Lancer!
no your not cheating... just that that car is not meant to be modified...