She said the Congress government in Delhi had tried to reduce carbon emissions of vehicles by implementing CNG.
While speaking on the occasion of conferring the Indira Gandhi Prize for Peace, Disarmament and Development, Sonia Gandhi said: "We who live in the capital, notorious now as the world's most polluted city, can recall the difference in air quality when compressed natural gas (CNG) was introduced for public vehicles."
"This transformation was made possible by the persuasive expertise of the CSE and the Congress government of the day," she said.
The award was conferred to the Centre for Science and Environment founded by Anil Agarwal and headed by Sunita Narain.
Sonia Gandhi also mentioned Indira Gandhi's contribution towards environment protection.
"In late 1971, even while being completely engrossed in the grave crisis on India's eastern border with Pakistan, she found time to initiate action that would lead to the passage of the landmark law to protect our wildlife. In the midst of all political crises, she found time to launch various conservation programmes of which Project Tiger has become the most iconic.
"She was the only foreign head of government to address the first UN conference on Human Environment in Stockholm in June 1972. Her speech there still reverberates. Indeed, it was in that speech that Indira Gandhi most powerfully and eloquently linked the three themes of today's prize, peace, disarmament and development," Sonia Gandhi said.
( With inputs from IANS )