Mine are all a good value for the services, convenience, safety, and/or pleasure they provide. They're all paid for, so it's just amortizing their cost per mile or per year. Plus insurance, which runs about $1-$2 per day low and high value vehicles. Maintenance is not free, but costs mitigated by doing as much myself as possible, and buying discounted parts and supplies (often in advance of actually needing them) when on sale/clearance.
For my "working" vehicles, I deduct the money they earn me. For instance, if my $10,000 car earns $12000 in fares this year, the net benefit of that car is $2000 profit. So the car paid for itself, and earned $2k.