But frankly, unless you specifically want a car which isn't viable as a company car, there's little in it financially and I value the totally hassle-free nature of company cars and not having to bother with insurance, road tax, servicing, tyres etc etc.
I dont believe that, unless you are not offered a cash alternative, which you say you are. Under every example i have run in my own and other peoples' situations there is quite a considerable amount in it.