Thanks Henros, I was thinking along the same lines, i.e. contributory negligence, as clearly the damage would not have been as great had the bumper support been attached properly.
The relevant statute for motor vehicles is the Motor Vehicle Standards Act 1989 but in it it refers to the ADR's which I couldn't find online. I wanted to get copies of the relevant ADR's before I got too carried away.
I did not put the bumper on, thats how it came to the country and thats how it was complianced. Clearly the duty of care for the engineer exists and it was breached. Although I knew that the front bar was aftermarket, I did not know of the changes to the vehicle's structure that facilitated its installation or its inadequacy for Australian regulations as I do now.
Would buying an imported car come under the Goods Act? Could this be considered "a good of unmerchantable quality"?. It is reasonable that I relied on the skills of the compliancing engineer to assure the structural stability of the vehicle. And surely it is not reasonable that during my inspection of the vehicle that I remove the bumper bar to inspect whats underneath is it? Thus it is considered a hidden defect. Two of the four tests for goods of a merchantable quality fail. Here the importer is considered the manufacturer, however it was not his fault as he wouldn't have known the changes to the underlying chassis, so maybe this doesn't apply then.
Should I succeed in some sort of action, however, it would open the "floodgates of litigation" for anyone with an aftermarket front bar who has an accident to claim damages from the installer or manufacturer. Then again, that is precisely the reason why the government has changed to the RAWS scheme, so maybe its justifiable.
It's definitely worth considering.
Does anyone have some definitive legal advice for me? Of course I claim responsibility for the accident itself but the damage is beyond what would have occurred to an ADR compliant vehicle.