This only involves state-owned vehicles. It may actually be part of a COST-SAVING measure, too -- if they are retrofitting older trucks instead of buying new ones. New trucks already have the low-sulfur diesel engines described here.
$6,500 per vehicle. Now, you have to do this to 30,000 vehicles. Thinking that it is a municipal union, how long would it take to do all of them and who would do the installation?