VIDEO - Why Are Cars Made to go That Fast?
This week on Twitter the question was posed about why we have cars that are capable of traveling at speeds significantly in excess of our posted speed limits? As luck would have it, one of the mailing lists that I subscribe to contained an article with a link to this video:

In cities, transportation agencies have long understood that motor vehicle speed plays a key role in fatal and serious crashes, and have sought to reduce speeds through design and regulation in order to save lives.
Ian Sisett was stopped by police for driving at an excessive speed near Grand Forks. He received a traffic ticket for that offence and the vehicle he was driving was impounded as required by 
Despite the fact that it is older technology, radar is still frequently used by police to measure vehicle speeds today. When used properly, it is an accurate method of determining how fast a vehicle is traveling. The courts also accept qualified radar evidence of speed during a trial as commonplace.
Holland has a serious pollution problem from nitrogen oxides and particulate matter in the air. The air pollution levels are above those permitted by European law and are mainly caused by motor vehicle traffic and factories.
The University of Waterloo has identified speed as the best predictor of crashes after analyzing data from onboard devices in vehicles. The research examined four aggressive driving behaviours, speeding, hard braking, hard acceleration and hard cornering for possible links and the likelihood of crashes. Of the four, only speed was statistically significant as a strong predictor of crashes.