It hasn't been that way for at least 30 years.
It has nothing to do with how fast a car can go. It has to do with how much you are likely to cost your insurance company. Therefore, a safer car is cheaper to insure because they won't be paying out for your death, and they'll be paying less for medical than they would if you drove a less safe car.
Case in point - I had a 98 Honda Civic coupe. Traded that POS for a 99 Mustang GT in 2002. My insurance premiums went down. The reason was the Mustang was a far safer car to be inside during a wreck.
In my case, nothing had changed but the safety of the car. The Mustang actually cost more, but the net effect of the increased safety lowered my rates. The Mustang could go far faster than the Civic, so believe what you want. And after owning both, the Mustang was far safer at any speed than the Civic.
Insurance companies use statistical data - not some half-assed conjecture based on stereotypes - to calculate premiums.