There have already been many reports from the field of some recent car bombers, where in the remains of the vehicle they discover a shoe (and sometimes a foot) duct-taped to the accelerator pedal, and hands duct-taped to the wheel.
These are not the signs of voluntary bombers.
Seems that "jihad" ain't selling like it used to.
There are also reports on Iraqi sites that 'jihadis' are not volunteers, but that Al Queda holds their families hostage.