It’s ok to drive 10% over speed limit
It is possible that vehicles speedometers have 10% error in overestimation. Law says it’s not allowed to exceed the speed limit. That doesn’t save anyone from being caught with mobile radar. The National Police Chief’s Council suggests police officers keep in mind error of 10% of the speed limit and 2mph for speedometer error. However, it’s only a suggestion, and they don’t enforce the law. Police forces have the last word if to use or not this proposal.