Now waiting for phase 3, this was a pretty enjoyable time passer. All of the tank size bonuses are really useless as is. By the time you fill up even the white tank, you could have done several more runs and the star multiplier bonuses are worth far more than the base 1 per 1000. As you accumulate more runs, this number increases even more.
It also annoys me that you use RYB as the primary colors, when it's really RGB and CYM for secondary based on how our eyes actually detect light. But that's me being pedantic.