Trackmania 2 Stadium is pretty much the ultimate Hot Wheels game already, and it's only $10.
Got that for $5 a few weeks ago. Even made some tracks that most would call "lame" and "not worth downloading".
Would recommend even though I dont see the big upgrade from United Forever, still feel worth it.
The handling is on the car in Stadium 2 seems much tighter, and the lighting/detail is a little better, but yeah, it's more of an incremental upgrade, kind of a d*** move for Nadeo to split up Trackmania 2 into separate environments selling for $20 each rather than a complete game for $40 or so like United, especially since TM2 is not radically different from TM1.