I think a level 5 car business is likely to be a poor way to make money.

In such a system your car is just a commodity, and people will take the cheapest option of similar condition. In such a system, there will be many people who own a car, but are so desperate for cash that they will rent their vehicle for less than what it costs to operate it.

They will sell a ride that costs them a $1 for $0.50 just to get their hands on that $0.50 now, even though it screws themselves over in the future.

Plus you will be competing with people who can buy the cars at a more lower price than use -- such as the car manufactures themselves, dealers, or taxi companies buying huge fleets of vehicles. So their cost of operation will be lower, meaning they can still turn a small profit while you'd be taking a lose.