text: In Bogota, Colombia- in a program that's set to spread to other countries, millions of Colombians hiked, biked, skated or took buses to work during a car-free day. Leaving the streets of this capitla city eerily devoid to traffic jams. The program is to promote alternative transpotation and reduce smog. Programs all over the world have been started to reduce greenhouse gas emissions. New York's new bike-sharing program and its skyrocketing proliferation of car-sharing programs across the nation. Diesel fuel was blamed, since France has a tax policy that favors diesel over gasoline.