Things to know about driving in Nicaragua:
-Things you're likely to see on the road and thus have to share the road with: 18 wheelers, other cars, trucks, SUV's, motorcycles, motorized tuk-tuks, bicycle-powered tuk-tuks, bicycles, walkers of all ages (3-80), backpakers, hitch-hikers, school children (lots of them), ATV's such as 4-wheelers, horse drawn buggies, ox-drawn carts, cowboys on horses, herds of cows, sheep, and goats, random wandering horses, random wandering cows, dogs (single and in groups), cats, chickens, roosters (fighting c*** ), goats, sheep, pigs, taxi's, "chicken buses", and those damn 3-wheeled red taxi's!  
-The rules of the road are most definitely only suggestions
-There is no such thing as a full and complete stop at a stop sign
-The stop lights go from solid green, to blinking green, to yellow for like 1 second, to red, back to green.
-If there is no one coming across the intersection at a red stop light, it becomes a stop sign...and sometimes even when there is someone coming across the intersection
-There are sales people at stop lights in cities, especially Masaya, and they sell everything you can imagine from sunglasses, to cashews, hammocks, to new windshield wiper blades...
-There are at least 2 kinds of taxi's: the official ones with the signs on top, and the unofficial ones which are just guys in their own cars.
-Taxi's stop in the middle of the road and take all the time they want to load or unload passengers, and you better not honk at them. But when you stop in the road in order to not run over a pedestrian, they will lay on their horn until you move.
-The road signage is sparsely located, unrealiable, often points in the wrong direction, when it does exist, is in the right place, and has the right info on it, it is ofter covered in graffiti so that you can't actually read it. And generally it shouldn't be relied on or trusted, except for the volcano evacuation route signs, those are reliable and surprisingly untampered with.
-Always reconfirm any verbal directions you get from a Nica with at least 1 other Nica, preferrably one that is not in the same group as the first person that gave you directions.
-The Nica drivers ARE better drivers than you, trust me.
-The cops often stand on the sidewalk and pull people over...not sure why anyone would pull over for them, they don't typically have a mode of transportation to chase after you, and they certainly don't have radios.