WRC 2,
It was never going to beat Forza 4 in sales considering it was released on the same day but it is still fairly enjoyable,
The biggest improvement over last years games are the graphics, WRC 2 is still one of the worst looking Xbox games ever but the graphics definitely look better.
When I bought the game, the guy that served me said "We have had nobody trade in this game yet" Now it's either the fact that the game is just that damn amazing nobody wants to get rid of their copy, or I am the only person to buy the game from that particular store? Well this photo I took below of the world XP leaderboard should give you your answer... and the fact that I have not seen more than 14 people playing online...
WRC 2010 and WRC 2 do have mediocre reviews but I do get a lot of enjoyment out of these games despite how very dated they feel.