See recent discussion here
There should be no bug in a recent version >= 0.7. If it still happens (your update seems to indicate this) it would be nice to have a small unit test reproducing the issue. A small speed value will block the access of the road too and therefore avoid this issue. To make it possible that e.g. 1km/h is not rounded downwards to 0, you will have to increase the resolution of the speed value e.g. do not pass a factor of 5 but use just 1 and increase the bits to lets say 7 and not 5. (done in the CarFlagEncoder constructor)
Again: without code and the actual problem I cannot give you hints what is incorrect. But yes, it should work 