Advocates of using public policy to reduce automobile use won't find much solace in a recebt review of more than 69 studies examining the effects of government intervention on a mode choice and travel behavior. The literature review titled "Can We Reduce Car Us, and, If So, How?" by several United Kingdom academics was published in the June 2011 issue of the leading professional journal Transportation Research Part A: Policy and Practice. Here's part of the abstract:
Sixty-nine reviews were considered and 47 primary evaluations found. These reported 77 intervention evaluations, including measures of car-use reduction. Evaluations of interventions varied widely in the methods they employed and the outcomes measures they reported. It was not possible to synthesise the findings using meta-analysis. Overall, the evidence base was found to be weak. Only 12 of the 77 evaluations were judged to be methodologically strong, and only half of these found that the intervention being evaluated reduced car use. A number of intervention approaches were identified as potentially effective but, given the small number of methodologically strong studies, it is difficult to draw robust conclusions from current evidence. More methodologically sound research is needed in this area.