In the 80's, due to the oil crisis, natural gas (NG) began to be regarded as a fuel with great potential for replacing diesel in heavy duty vehicles. At that time, Petrobras, together with other companies, developed conversion kit technology for heavy duty diesel engines to run burning simultaneously diesel and NG, known as diesel gas. For several reasons, the trials were interrupted. In the late 90's and beginning of the 2000's, factors such as NG availability, expansion of NG distribution network; increase of NG converted light duty vehicle fleet, government interest in increasing NG's energy matrix share, all together made a scenario which stimulated new developments in diesel gas technology. The scenario changed in the last couple of years, with Brazilian NG demand reaching its offering, mainly due to thermoelectricity generation guarantee of supply. This makes the diesel gas technology more attractable than the NG dedicated technologies. Moreover, LNG importation and internal production increase prevision makes this a transition period that do not impact medium and long term developments. This article presents some works developed in Brazil with diesel gas technology, its evolution along the years, mainly to comply with more restrictive emissions limits. It also provides an brief insight on the emissions regulation in Brazil, showing technical points that should be discussed in order to consider diesel gas applications in technically sound bases. Specific regulations on diesel gas emissions are required in order to guide sustainable developments in the area.