I've driven a Prius a couple of times, and I concur that they have an acceleration problem. I step on the gas pedal and the car has problems accelerating. (rim shot)<p>OK, back on topic. There's all this talk of cars accelerating out of control. Almost any car with disc brakes is able to overpower its own engine... for a little while. The biggest problem is that a wide open throttle means there is no manifold vacuum, so the brake hydraulics will be unassisted after pumping the brake pedal a couple of times. If the car is still at speed and the throttle is wide open, it will to be a lot harder to stop.<p>The problem of uncontrolled acceleration is due to a failure of multiple systems in ways that car designers didn't predict. All of the following are required for a car to accelerate uncontrollably:<p>1. An automatic transmission. In a manual the driver will hit the clutch and brake pedals to decelerate.<p>2. Hydraulic brakes powered by manifold vacuum. Electronic-assisted brakes are less reliable overall, but they will work reliably if the car's throttle is wide open.<p>3. Keyless ignition and lack of a BIG RED KILL SWITCH in a standardized location. Industrial equipment has them. Motorcycles have them. Why don't cars have them?<p>Each of these things alone seems like a sound decision. Automatic transmissions let drivers focus on driving instead of shifting. Hydraulic brakes are usually reliable, and they use manifold vacuum that would otherwise be wasted. Keyless ignition is convenient. But together these systems (coupled with a panicked driver) can fail in unexpected ways. I'm not trying to excuse Toyota, just pointing out that this sort of thing could have happened to any car company.