The biggest difficulty with rally sims is that you don't know whether you are going uphill or downhill. In circuit racing, it's pretty much flat, or you can memorize the course very easily, and they loop around. So you don't have much problem with just visual input. The incline information isn't something that you can easily express easily with visual information alone, that's why you need an actual sim rig that helps with the G force a bit to give you additional information. The only other way to get it right is to repeat the same course, which defeats the whole purpose of talking about incline information since you just improve through practice and repetition.