Paris (as a municipality) is a small footprint city when compared to other capitals. A central matter for the current French planning scene is how to ensure a coherent urban project with an administrative fragmentation, in which Paris has 2,2 million residents and an additional 8 million residents live in hundreds of municipalities seldom over 50.000.
Public transportation is essential. Noisy- Mont d’Est is a RER (a kind of metropolitan rail network) station created during the 1980s to serve what was to be the center of one of the new towns whose inception can be traced back to the Gaullist 1960s. As a child I saw the station, the neighborhood and the lake being built… and over time I have seen what was to become a city core fail somehow, despite a strong public cash injection. In part the station contributed, as it had a clear functional project linking rail and bus, but an architecture that relied on scarcely lit underground spaces that contributed to a climate of insecurity (one of the factors fueling the “seismic” result of last Sunday European elections).
A renovation program has moved the station outside, limiting the underground spaces to the platforms themselves, leaving the buses on open air. I’m not sure to see the centrality of the area improve that much (despite the fact that employment exists), but many people can use the bus with a different feeling.
Centrality is in such places a more complex issue: those new towns have obtained over time a set of roles, including universities and corporate headquarters. But two factors have played against these projects up to date. On one side, a configuration in which, despite a presence of public transportation, car has remained central. On the other side, the asymmetry between a public power that is to make its strategies explicit through planning and a private sector not bound to this, which has, especially in the first years of the new towns, having no constraining laws, created big box retail in peripheral locations that prevented other retail operators from locating in planned centralities. And an urban core without a strong retail base is a complex thing to get…
metrhispanic 
Hartford, CT, the much, much smaller urban Capitol near me faces the same problem. they are trying to plan for improving, perhaps moving an aging overhead highway that cuts the city in half but it also crosses the rail station. Future plans include the addition of light rail and a ‘busway’ but as you mention, cars will dominate. I’m not sure if our problems resulted from bad planning or no planning, but today we certainly have the problem.