THis is a scam. I just read about this in Consumer Reports and DO NOT RESPOND to this person. He will take your money and run. Next time you get a message like that, don't even respond to it. Delete it ASAP.
Other types of scams are when a person who says he's calling from your credit card company or bank. THis person calls you, sound very officious and real, saying someone has charged a lot of money to your card and they want to correct the fraud. They then verify your credit card (they already have the number), and then they say they need to verify the THREE DIGITS ON THE BACK OF YOUR CREDIT CARD. NEVER NEVER NEVER give this out. The thieves need the three digits in order to use your card. The next thing you know, you will get a charge on your card for a huge purchase.
No bank or credit card company should EVER have to 'verify' your account numbers. They should have it on their file.
If someone calls from your bank or credit card company, say you will call them back. Then look up the number from an independent source, and call the company back yourself.
Other places to sell your car: another mom posted a similar question on 8/8/7 and got many responses.
Other scams I've read about is the "nigerian" scam, where you get an email asking to wire some money over so that 'sick' person can come to USA.
It's good this incident made you suspicious. GOod luck!