Brighton and Hove Albion's plan to build a stadium at Falmer is flawed and should be scrapped, opponents told the public inquiry into the project.
Sustainable transport expert Alan James said the proposed site at Village Way North would be the wrong place to encourage fans not to use their cars to get to the 22,000-seat ground.
He said supporters would be more likely to use public transport or walk if the stadium was built at another site, such as Shoreham Harbour, Hove Stadium or Toad's Hole Valley.
The comments came as opponents started to make their case at the public inquiry into the plan.
Mr James, giving evidence for Falmer and Rottingdean Parish Councils, said: "The Village Way stadium development starts with an unsuitable location for sustainable transport.
"It is difficult to envisage a travel plan that could overcome the basic problem of location in order to deliver an acceptable proposal."
He said Brighton and Hove City Council would not be able to enforce planning conditions to restrict car use and that meant planners had doubts about the scheme.
He said the council's response to breaches of similar conditions at Withdean had been to "move the goalposts".
He said 75 per cent of journeys to Withdean were originally meant to be by bus, train, bicycle, or on foot.
The figure was later cut to 55 per cent, although the club is struggling to meet a target of 50 per cent of fans using sustainable methods of transport.
Mr James, speaking on the 17th day of the hearing at Hove Town Hall, said it was unlikely non-car transport would pass 30 per cent at Falmer.
The club insists Falmer is the only suitable site for its much-needed new ground and there would be severe traffic problems if the stadium was built anywhere in the urban area.
Jonathan Clay, representing the club, said there was no threshold where transport to and from any particular site became sustainable.
He said Falmer was extraordinarily well-placed for public transport and none of the bodies responsible for roads believed there would be problems.
The club said car use could be controlled.
The inquiry is now expected to continue until at least June 6.
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