
If you decrease your speed and practice, I guarantee you it will work out. Dynamic braking might help... but we aren't using it because we are somewhat satisfied with what we have.
Edit: extra note, we were stuck at around 20 cm off for a really really really really long time. over time, when u practice, pay attention to what the issue is, and just keep trying small things to change it. One thing that impacted our car's accuracy for the very first time we run it after removing it from the box was the way we positioned the wingnut in the box. Theres a lot of factors to consider and account for