Well yeah, but if there's 1,000,000 of one type of car on the road vs 10 of another kind (extremes of course, not actual figures) then chances are an awful lot more of the 1,000,000 are (not would be) being crashed more frequently...
You could pretty much base it on the number of each type of car you see in scrapyards, can nearly always guarantee a Passat or 2 or 3 in any big yard, I can't remember the last time I saw a MK2 rocco in a yard!
The low numbers of certain cars means the ones that are left are being driven more carefully, and generally being looked after better and as such are cheaper to insure regardless of power.
As for the same being true of modern cars where there are still 1,000,000's of them with various engines, and the more powerful ones are cheaper to insure - kids can't afford to buy big power cars so therefore there are fewer bellend/careless/inexperienced drivers behind the wheels of the faster models
Statistics! I don't know why people don't get it!