I have no money so it doesn't apply to us mere mortals but I guess if your a big time investor I guess the question for the tax man is wether a car is a reasonable expense to claim for going to see your investment people or for check out local investments like coffee shops, restaurants and movie theatres?

No wonder there are so many accountants

Here is an interesting globe and mail article with a humorous Hockey twist

Holding companies have their benefits - The Globe and Mail

Yes, it is allowable, provided you have a legitimate reason, but the personal use is a taxable benefit. In my example the personal use was 100%. Lots of people who get company cars have a second car for personal use. You would have a hard time claiming 100% business use without a second car.

It appears OP has made his decision and I agree with it. Based on the facts we have been given, the tax cheat sounds like he/she is living fast and loose and is being blatant about the cheating, so will be caught eventually. Turning them in now might actually make the end-game easier on him/her. Better to let them continue to dig a deeper hole, build a bigger house of cards. Will be much more satisfying when it all comes tumbling down...inevitably.