I nearly died!
It was Falcon XC GS Coupe I was looking at to buy.
It was on top of a steep driveway, on the footpath crest, so easy to get under from the back. It had 4 wheel disk brakes and the seller said the handbrake was sticking.
I said no-prob and climbed under, from the back, and used my finger to release the stuck caliper hand brake lever.
The car lurched backwards, but lucky it was an auto and it was in "Park", and lucky the Park Pawl in the auto transmission worked!