Nigerian traffic is chaotic. The bigger and the faster cars try to overtake one another. There are a lot of motor bikes. If the motor bikes would be cars there would be traffic jams all the time. There are rarely traffic signs. Even if you see a traffic sign somewhere most people don't know its meaning. They do not obey traffic laws.
We saw a lot of cars used in Germany before they were imported into Nigeria. Some have broken front windows, faulty lights or seat belts - no problem as long as the horn is working. Without horn driving is very dangerous in Nigeria. You need the horn to call people's attention. "Horn before Overtaking" is written on some trucks.
If you can choose you should take a car with air conditioning. AC is not only comfortable for high temperatures but also because of smog and dust. Not every road has asphalt or the asphalt cover is broken. That is why cars cause a lot of dust around the roads during dry season. That is annoying and can cause a running nose. If you don't have the opportunity to use AC you should not become thirsty - drink a lot. When being thirsty the possibility of getting running nose is even higher.
When travelling into the cities, policemen can stop you at will. They may use a "natural" blockade or make their own by putting trees on the road to force you to slow down. They don't really do something important. They just look at you and some policemen delay you till he gets some money (20 Naira) from you. Because of their arbitrariness policemen have a very bad image in Nigeria. They carry heavy guns and that is why they get the necessary respect anyway.
For me as a middle European man it is impossible to drive in Nigeria. Not only because of the chaotic way of driving, but also because the policemen will take special care about you. Even if you don't drive they may charge you an extra fee (50 times the official fee) when the driver committed a little driving offence.