Here are the walkthrough for Push Cars iPad game, round 2 for the City of Houston. Take note of the direction where the cars are facing.
In this level, there seems to be some "bugs." Using the same setting, most of the time, blue Sparky can't pass clear yellow Hannibal. But sometimes, as shown in the picture below, it will, and eventually, it must!
Watch this YouTube video:
Now, without the help for the Push Cars walk through for these levels, try to play them again, all by yourself. Enjoy!