Prize cars that do well are the Lancia Delta '94 and the Mitsubishi Pajero Rally Raid(I came closest to beating Grand Canyon Hard with that car). The Lancia Stratos is also pretty good on Swiss Alps.
But honestly I would sell some of the easier cars if you're strapped for cash and buy a Peugot 906 and tune it, or (better yet) the newest Subaru rally car. And if you really want it easy, the Mitsubishi Evo Super Rally Car leaves everything else in the dust.