Rental car insurance coverage is a HUGE rip off. Generally (you do need to check) your own car insurance covers you for a rental car just like you were driving your own car. The only danger to you is if you wreck the rental car you're going to be paying your deductible. But think about it, if you're driving your own car and you wreck it you're going to have to pay the deductible. So would you elect to pay $24 a day (or whatever it is now) to drive your own car just do you don't have to pay your deductible if you got in a wreck? Of course you wouldn't. So why pay it for a rental car?
And like others have said, check the benefits on your credit card. I think your own auto insurance would be the primary coverage and I think some credit cards have coverage that pays the deductible.
And no matter what, if you get in a wreck and there is a police report or an insurance claim it's going on your record and your own company is going to find out. That happens no matter what car you are driving, even if you are driving an employers car.