This costs a bit in bank fees and legal costs but does give you a great deal of control over the process.
Buyer & Vendor agree on a bank (yours of course) which holds the funds in Escrow pending all the DVLA, HPI, Police etc,etc checks.
Bank will only release the money once you have formally confirmed that all is in order. That means you must know what conditions he needs to satisfy before you start. If vendor is genuine this should not be a problem: he has made a legally binding (conditional) sale and knows the money is held in safekeeping by a trustworthy third party (the bank) only until he can satisfy you that he has good title.
If he fails to satisfy your enquires the contract fails, you instruct the bank to terminate the Escrow arrangement and return funds to your account. Then notify the Police of an attempted Criminal Deception.