According to some Global Peace Index, Malaysia is the safest country in South-east Asia, and 19th safest in the world.
This family may disagree: http://mrbrwn.co/N37PhS.
Nonetheless, there are safe ways to travel to Johor. You just need to make some small modifications to your vehicle.
A Facebook commenter said: "Even non-Johor Malaysians don't want to stop in JB after dark."
We should heed that pro-tip.