What percentage of the driving population drives less than 9,000 Km (5600 Miles) a year? Motorcycles might be a good fit due to the seasonal nature of the beasts but cars????
Maybe the downtowners in their condos?
Using GreyGhost's assumptions and my pleasure use car policy of about $1200.00, start with $600 up front plus 17,000 km / year (9,000 allowed no charge). 7% X 1200 X 8 = $504.00. Add that to the base and $600 + $672 = $1272. Doesn't work for me and I think GG's assumptions are reasonable.
Using the 20% /10% becomes $240.00 base + ($120.00 X 8 units) = $1200.00. Now we're a match but any change in pattern could put me underwater. I like flexibility.