Many people ask Lawson about the drive from Cancun to Merida and vice versa, and is it dangerous. The response is always the same: the most dangerous part of the highway is falling asleep at the wheel and having your foot weigh down on the accelerator, thereby resulting in a spectacular crash event involving you.
Below is a short example of what the entire 3 hour drive is like, with the exception of the stops for tolls (2) which will set you back around 600 pesos. Cash only.
At night, after 7pm, they offer coffee. However, it often runs out and then 'no hay'. Apparently it is too much of a stretch for the folks manning the booths to have 'coffee making' included in their job description. Or maybe that would put them in a different, higher, pay grade and no one wants that.
Remember to watch the whole thing, not because anything exciting ever happens, but because you want to get a real feel for the drive before considering it yourself. Oh, and at night it's even more interesting. Not.