The average car insurance premium in the US is over $2000/year, and over $2500/year for full coverage. I imagine that has an outlier effect and the median is lower, but I'd be surprised if the median was under $100/month. I'm paying just under $1000/year (and yes, in Ontario).
It depends where you live and how much coverage you get. The real kicker these day is uninsured motorist coverage, because so many people are driving without insurance and they are much more likely to get into accidents.
You must own your vehicle in its entirety to be able to downgrade to liability-only. If you are still making payments on your car (which most people are), your lender requires that you maintain full coverage.
