I tried the city and zero and here are my thoughts
The City:
Obviously fairly early on in the project still, the car phystics need to give a different feel when getting into different cars, also the players cars wheels dont turn, the traffic is perhaps a little too congested and the Fiats wheel turns are bugged.
I'm not sure how big the city is, but introducing some new fractal rules to create some diversity would be a good idea, such as a highway section, an industrial estate, a housing area etc.
Zero
Quite a smooth little game and I enjoyed it. The installer only placed an uninstall on my start menu (I specified my own path), therefor giving me no meens to run the game without navigating my hard disk. The trails version of the game needs to either test if you are moving when placing a trail piece or to force a minimum move speed. Overall a nice smooth game, although obviously only a small project with a few more ideas in there it could have some replayability
Good stuff.
God created the world in 7 days, but we're still waiting for the patch.