I think you are right, this is the reason why some new stuff is not coming fast, but it's coming. It's difficult dealing with other people's code, but after you reach the point you've mostly mastered it (in whole or parts of it), then you can do anything. Remember, the Madness engine in PCARS2 has probably the worst FFB among sims ever known to man, but it's mostly fantastic in AMS2, PCARS2 has a ridiculous behavior of cars over kerbs, this works just fine in AMS2, PCARS2 has the worst track limits/slowdown system ever conceived, but Reiza has modified it to something that is already working much better in AMS2 etc etc. So definitely more is coming in improvements over the engine problems and missing features. Regarding some of your points: -(separately) Adjustable Mirrors: I suspect this is an extremely difficult one by definition, because it would mean calculating and displaying the world through 3-4 different angles (the forward one and 3 different ones for mirrors). For a very low gfx quality game this could be possible, but if you expect the mirror image to be comparable to the forward one, then this would be extremely GPU heavy and I suspect that probably this one will never happen indeed. I have no insight on this, just my guess on the matter. -Replay, I think I've read somewhere that SMS attempted to actually "fix" this before releasing PCARS2, but they failed and had no time left to properly do it, before the sim was released. I would bet Reiza will deal with this one eventually, but it will just take some time, as I guess it's not of the highest priority. -Multiplayer features: Already Reiza made several improvements, in the car collisions, penalty system, accidental "exit race" problems etc. There is still A LOT that needs to be improved, but it looks to me that this aspect is also improving (although indeed slowly unfortunately).