Quite often, I have just grabbed the keys to my car and used it for work stuff. After all, it was easier and I could be reimbursed for the mileage, so it wouldn't cost me anything... and any place other than 8 miles up a dirt road, it might even make me some money.
My insurance guy kept telling me that my insurance policy had a "clause" that prohibited work use. What I've come to learn is that it actually means: "We won't cover you if you... you're on your own because it's either best insured elsewhere - or you should be paying more for that coverage."
If you've got a work exclusion in your policy (like I do) and you do use your vehicle for work stuff (even if it's just errands or picking someone up from the airport), you might not be covered. You're essentially "retaining" your risk... willing to pay for the damages if something happens. But there are ways to solve that... it just depends on your situation and the company's policy.
