I use my car for work, which isn't in my job description or contract. I have damage on the car and my employer want me to use my ins? Is this legal?

I accepted a position with this new employer who recently asks me to start using my vehicle to obtian clients. This duty was never in my job description or in my contract. I agreed to visiting clients or potential clients periodically and I also agreed to them paying for the mileage when doing so. I'm now constantly on the road and now have damages on the vehicle, while on business hours. They first ask for 3-4 quotes for the damages which i provided over a week ago. But now I'm being told to go through my insurance policy. Is this legal? Should i be going through my insurance for these damages?