When I define an Expression for the rotation of a wheel, then I have the problem that the wheel doesn't rotate unless some variable value referred to to in the Expression changes.
For example if I enter a total distance to be travelled (toPath length) / circumference (plus a formula for compensating when the vehicle turns), then no rotation of the wheel occurs as long as the path is straight, that is, until the vehicle turns and so the angle variables gets changed values.
It means also that I cannot make the wheels rotate with an Expression if simply entering the value for the (total) number of revolutions (like entered in the X, Y, Z fields on the timeline).
Is this as expected? Unfortunately this means that the Expressions only works "sometimes" and sometimes not (perhaps a workaround for now could be to tweak Bongo by making something rotate during the animation as to provide with "changing values").
I also noticed that if I enter a value in the Rotation property, I do not have access to other object's Position properties, even if they are accessible in the editor. This also seems odd to me.
Perhaps Bug 1 & 2 could be addressed in a service release? It really would help a lot.