Somewhere in the not too distant past auto manufacturers ditched the carburetor for a microprocessor control injection system to put a mixture of fuel and air into engines of modern cars. When that was done a monster was created, the modern throttle body (seen in the lower left quadrant of image below).
You will notice a cable running to the throttle body, the trouble with cables is that they can
pull but cannot push. Old carburetor engines throttles consisted of spring loaded solid rods that could pull as well as push.
Below is an image of the inner venturi of the throttle body, notice the carbon that has built up inside of it that will eventually prohibit the butterfly valves to move. And when that happens you can't kick it back into idle mode like an old carburetor car. Now you will run into another modern monster: vacuum assisted or power brakes. The vacuum assisted braking system would be more accurately named the "foot assisted" braking because without the vacuum you cannot deploy the brakes adequately.
Now you have a worst case scenario: throttle stuck open, brakes won't work. If you are very fortunate you will have time to switch off the ignition (provided that you don't have one of those push button starter where you can't switch off the ignition) put the vehicle into neutral and deploy the utterly pathetic parking brake.
THIS IS TRUE OF EVERY CAR MANUFACTURED USING MICROPROCESSOR CONTROLLED FUEL INJECTION RATHER THAN CARBURETORS!! AND THAT MEANS VIRTUALLY EVERY CAR ON THE ROAD TODAY!!!
So why don't the dealers, Congress and Toyota tell us about it?
Because they'd have to recall every car on the road regardless of manufacturer and
they don't want to incur a crippling class action lawsuit.
You can probably recall some old bastard telling the press and court system that his
throttle stuck and he ran over pedestrians as a result. Seems like I hear about one a year. Then there are the unfortunate ones who drive through a building because they are in the process of parking. Of course everyone grins and thinks: oh sure, another lame excuse for tragedy...must be a conspiracy theorist or UFO chaser.
After the unfortunate incident, no evidence can be found to substantiate the driver's claim of stuck throttle and no brakes. But it has happened to me several times with several cars. Fortunately for me my mind was prepared to respond and had space to do it in.
So how can you protect yourself from such a nightmare?
Have the throttle body serviced every 70K miles by the dealer, and keep the work order because many times dealers claim to do things they don't and you will have no way to prove whether the job was done correctly.
So why don't the dealers bring the subject up and recommend such a service?
LITIGATION, LITIGATION AND MORE LITIGATION.
So as Ralph Nader said "unsafe at any speed."
Operating a motor vehicle is the most dangerous thing you can do, so take heed Transmoglydites!