No one should ever get your full VIN. I've seen both Ebay and Craigs list posting vehicles for sale and they give a vin number saying they are selling cheap because of any number of reasons. When you contact them, they say they are out of town with a prospective buyer, but will sell to you if you wire the money. You send the money and never see the motorcycle or car. When you file with police, it has been sold to dozens of other people too. The person advertizing posted it in many different cities, and the real owner of the vehicle now has a huge headache of paper to deal with if they really are in a sale agreement. Even if the original poster pulls it and then goes to renew registration later, DMV may have it flagged. I've only seen that scam once on a Harley and once on a Sporty car, but suspect a strange request like this could be how they started it.
