[Treeve]

Seatbelts still have some give in them, and hence once crashed, they will have a deformed length - much longer than when you have put them on when you were wearing them. There is also a certain amount of movement in the design - the long part form the floor to your buckle, which will alow your hips to move (unless really correctly and tightly adjusted), the amount that travels from the inertia reel as you come to a stop, and then also the amount your head and torso 'whips' past the belt into the dash.

Lets also remember that US market air bags are larger than Aus / Euro market cars, for the simple reason that the use of seatbelts in the US is considerably lower than in our areas, hence the air bag sizes and deploy rates are higher to allow for people not wearing seatbelts.

The installation of dash padding is to minimise to as low as reasonably practicable the risk to users of the vehicle - it is reasonable to put in practice dash board padding to protect users of the vehicle, hence why it is done. It is not practicable to install air bags and the like in low volume / kit / home build ICVs, due to the rigorous and expensive testing required, hence why we don't have air bags.

Treeve