"This is the third time we have had a car come through the hedge "
yeah...well after #2 at the least, i would had bollards put in. sounds abit like these people w/ houses near rivers that get flooded out year after year but never seem to put in any flood-handling features.
aside from that, the VW does sound dodgy, but surely basic forensics etc would be able to determine the guy's speed due to the damage sustained etc?