Let me get this straight...
He did transfer the car into his name? Or he didn't?
If he hasn't bothered to reregister in his own name, walk away.
If you buy it, whilst he does have it registered in his name, get a "Bill of Sale" off him with the statement that it's unencumbered.
After getting Rego No, VIN No, Engine No, contact VEDA (that includes REVS) for vehicle history.
And like 25GTT says above, you can pay for a proper inspection of 'his' car at his home. If power is down, compression test may reveal how tired the poor thing is.... yaddayadda... > if it's tired, walk away.
In this economic climate, the seller should be chasing you!