Regulations on seat belts did cause accident rates to rise..
Accident rates? Maybe. What about accident fatalities? Increased feeling of safety (which might result from actually being safer) could cause people to have more less-harmful-than-fatal accidents.
Not to mention, where does the government get off on telling people what to do in their own automobile?
The government only gets to tell you what to do in your automobile while you operate heavy machinery on a government-owned road. It also, for example, tells you what you may or may not do in a court room (like you can't sit and read a newspaper in there). What you do in an automobile on a private road or how fast you drive it on a private race track is not something that the government restricts.
Happiness is twin floppies.