As talk of tax reform grows, operators may have limited time to see these savings .
Fee would supplement gas taxes as fleet becomes more fuel-efficient .
Study shows Philly CSD, energy-drink purchases have plummeted
4 legal actions and an effort to repeal
New system could replace gasoline tax as road-funding mechanism
Class-action lawsuit contends sweetened-beverage tax misapplied
Decision could determine constitutionality of municipal fundraising efforts
Why pollution taxes may be more of a reality now than at any time during previous presidential administrations
A look at where regulatory devices are under consideration and where they could soon become reality