An Interior Ministry spokesman, Brig. Javed Iqbal Cheema, said Bhutto
"fell down or perhaps ducked" and apparently hit her head on a lever
connected to the car's sunroof. Cheema added that the lever was stained
with blood. His statement followed with the scientific logic that due to explosion by the suicide bomber, the blast wave which is infect very powerful can push Benazir so hard to the lever that it can actually fracture her Head. But the fact is quite different to what Govt. has predicted

Below is the video that shows the last seven minutes of Benazir's assassination, Things that you should notice in the video is the gunshots and how soon Benazir Ducks into her jeep, if the blast wave was suppose to push her to hit her head to the lever then for that to happen she should be outside the jeep when the explosion takes place. But the video below clearly indicated that as soon as the shots were fired she ducked in and then after a second or so the blast takes place.

Real Video in slow motions of Benazir Assassination