I know the price in Belgium for insuring a car. Example was for a €25.000 car:
€1750 fee per rally (strangely it didn't matter whether it was a rallysprint of 4x10km or a 3 day rally...)
The first €2500 of damage were not covered by the insurance and had to be paid anyhow.

As I understood, these were fixed percentages and did not depend on the car or driver.

In Belgium it is very difficult to find someone who wants to insure you. I know of only 1 company who does this in the Flemisch part of the country.