Hey,
When considering the option of taking a company car, be sure to ask to see the fleet vehicle policy (they may have another name for this) and read it IN DETAIL.
I also have the option for a company car, but it does NOT cover travel to-and-from work. It does, however, cover travel to other locations during my workday. I must reimburse 22 cents for each personal mile (including to-and-from work each day, as my policy states).
I am not responsible for insurance or large repairs, but I am responsible for upkeep, which includes washing and cleaning, oil changes, tire rotations, and inspection (and small repairs to pass inspection- wiper blades, headlight adjustment, etc.). I am also responsible for all gas for the vehicle.
I added all of this up and came to the conclusion that a small and cheap run around vehicle that gets good gas mileage and I use a company car whenever mine is in the shop, which is a nice option to have.
I may reconsider this when my vehicle starts needing more and more money put into it, or I may request a negotiation of the fleet policy at my yearly review, but for now after looking over the policy in fine detail and doing all of the math, I'm sticking with a personal vehicle.
My savings was about $900/yr through this choice, barring massive repair needs.
Good luck! It's great when companies offer perks to employees.