Mashed had 15 tracks and that never felt like enough, me and my friends played them to death and really needed a few more. 6 seems a pitiful amount for Wrecked, especially as there aren't highway/traffic themed levels.
Why is six tracks pathetic?
For me the tracks aren't really that important, it's what's happening on them that matters and that's 90% from the players except Polar Wharf (or Ice Bridge as I think it's known now). This is a combat game first and a racer second.
I'm not apologising for the game though, just giving my point of view.