The issue is that no real buyer will offer to buy a car sight unseen. How many cars have you bought sight unseen? I wager none, so why are you taking the email you received seriously?
Unfortunately many people do, they are trusting and looking to sell their goods. The main and number one issue even aside from "site unseen" is to never ever send cash overseas via Western Union or Money Gram or QChex or anything to someone you do not know that has sent you a cashiers check or some sort of paper payment that could turn out to be counterfeit, don't do it- you will be stung.
I intend to search the ads, go and personally look at the car to make sure that I am not being scammed (how is that for reverse role play?), bargain the price and pay the seller in cash and collect both car and pink slip and then ship to Nigeria
Forgive me, but I am having a hard time believing that is worth your time and money to fly to the state that you are going to pick up your SUV and bike (maybe (2) different states) pay the seller in cash and ship yourself and the goods back to nigeria, this seems costly and fishy.