There was only one occupant in 75 per cent of all cars travelling into Dublin city during peak times, according to research carried out by RAC Ireland for The Irish Times.
The results show 80 per cent of cars coming from the south via Donnybrook carryied only the driver.
More than 75 per cent of cars entering Dublin from the west along the Naas Rd were carrying just one person. And only 30 per cent of cars coming into the city from northbound routes through Fairview had more than one occupant.
Minister of State at the Department of Transport Ivor Callely said the results were disappointing. He encouraged people "not to be entrenched and say 'I always use my car'."
The Minister was also critical of Dublin City Council's refusal to take part in tomorrow's car-free day. "It wouldn't have taken much for the council to endorse the day. You don't necessarily need to go out and spend money or close streets."
Last year the council was criticised after commuters claimed that pedestrianising some streets had worsened congestion. Car-free day marks the end of European Mobility Week which was celebrated in 34 cities and towns across Europe.
Mr Callely said the argument that "public transport was unreliable" was no longer accurate. "In reality car-free day is down to the commuter and I'm asking them to look at alternatives on Thursday."
To encourage car-pooling he has asked the city council to consider a trial of priority lanes for cars with more than four occupants. However, he again ruled out the introduction of congestion charges.
However, Mr Callely accepted there is a capacity problem with park-and-ride facilities in the capital. There are fewer than 4,500 spaces for the entire city, all at suburban rail or Luas stations. An estimated 230,000 cars come into the city each day.
To address this shortage, Mr Callely wrote in July to all senior local authority managers and transport providers asking them to consider any application for capital grants for park-and-ride facilities for rail services and along major bus corridors.
"I'm not accepting the Dublin Transport Authority (DTO) position of facilities at railways only. I'm saying 'give me a proposal for rail and bus'.
"We should have park-and-ride geographically, strategically located throughout the length and breadth of the city, not just in the suburbs."
He has identified a number of sites which are either owned by the transport provider or the local authority. "Let's identify sites such as these and develop them first. There will be occasions where we have to buy and, yes, there is a business case that will have to be looked at for the park-and-ride policy. If we are to encourage private investors, we will need an appropriate charging mechanism."
Jerry Purcell, head of RAC Ireland, said the car occupancy survey showed the lack of infrastructure for commuters, in particular the lack of park-and-ride facilities. "We simply don't have - nor will we probably ever have - a public transport infrastructure that will eliminate the need for people to have cars.
"This survey shows that initiatives like car-free day can only ever be a cosmetic exercise in Ireland," he said.
