We would like to share the findings on this important question from an international research report:
The instrumented vehicle study conducted by TUV and DLR (Germany) and Virginia Tech Transportation Institute (the USA) was designed to be comparable to the instrumented vehicle study conducted in the Netherlands by TNO (Vonk et al., 2007). The effects of [...]

In 2006 TNO performed a study into the effects of driving with a navigation system on traffic safety in the Netherlands with four different research methods (see Vonk et al., 2007). Overall the results led to the conclusion that navigation systems have a positive effect on traffic safety.
TomTom has asked TNO to repeat two of [...]