When a cruising taxi operates an approved shared ride / carpooling service in a municipality that explicitly permits it, what is the statutory condition regarding the fare charged to each passenger?

1. Each passenger must pay 100% of the full single-passenger meter rate individually
2. The driver may charge any arbitrary cash amount without issuing receipts
3. Fares must be calculated and discounted according to municipal carpooling metering rules, and all onboard passengers must explicitly agree to the carpooling arrangement
4. The first passenger rides for free while subsequent passengers pay double