Cody Jeffery (22) and Rebecca Gibb (24) have gained 900 supporters since launching a Facebook page, Dunedin Sober Drivers Save Lives, on Tuesday night.
''We are just trying to stop the deaths from people drink-driving - we've had enough of it,'' Mr Jeffery said.
The campaign follows the deaths of Mosgiel siblings Danielle Ngametua Kiriau (17) and Shannon James Kiriau (22) in a car crash on the Southern Motorway in Dunedin early on Sunday.
In December, Dunedin police warned about 60 drivers who were offering passenger services organised on Facebook.
Passengers paid fees or bought petrol in return for a ride.
Mr Jeffery said yesterday the group wanted more, cheaper, options for people to get home.
He believed the law about passenger services was unclear.
''If someone picks up a hitchhiker from the side of the road and the hitchhiker flicked them $10 or $20 - or what they can afford for fuel - is the driver eligible for a $10,000 fine?''
The group was not trying to to take income away from taxi companies, he said.
But Dunedin police said they would never support a criminal activity and drivers and passengers using an unlicensed service faced hefty fines.
Dunedin road policing manager Senior Sergeant Phil McDouall said a driver must hold a passenger service licence to legally carry passengers, on any road, for hire or reward.
For a first offence, a driver and passengers could be fined up to $10,000 and for a second, or subsequent, offence, up to $25,000.
The vehicle could be impounded.
''We want to discourage this - there are perfectly good taxis out there.''
Snr Sgt McDouall said police supported people who put money aside and arranged a safe way home before heading into town to drink.
''We do not support the drunks who go out there and solicit a ride from a complete stranger to get them home, because they are both committing a criminal offence.''
New Zealand Taxi Federation spokesman Roger Heale said although it was legal for a sober driver to collect petrol money from friends, it was illegal for a driver to hire themselves out as an occupation.
''It's one thing to take your mates down to the pub, not drinking and them buying you Coke all night and paying for your petrol.
''It's completely another, you getting in your car on Friday and Saturday and actively seeking carriage, or to take people for a donation, or a fee.''
Paying a taxi fare was much cheaper than paying a police fine, he said.
''And you don't have the risk, you're fully insured, and you've got a compliant driver, company and car. Why would you run the risk?''
Last night, two of those injured in Sunday's crash remained in Dunedin Hospital. Back-seat passenger Courtney Donald (17) was still in a serious condition and driver Cameron Presland (20) remained under assessment.
