The case was registered at the Nagpur City Cyber Police Station following a complaint by Shishir Tripathi, president of the BJP's social media cell in the city.
Besides Kashyap, the FIR names Instagram account Desi Boys (desi_boysncr) and influencers Harshit Rathi and Ankleash Invatee.
Complaint alleges misinformation, defamation
According to the complaint, a YouTube video uploaded by Kashyap on July 3 contained misinformation intended to mislead the public about E20 fuel and tarnish Gadkari's reputation.
Tripathi further alleged that the three other influencers used abusive language against the Union minister in videos discussing ethanol-blended petrol, with the intent to spread false information, defame him and disturb public order.
Kashyap had joined Prashant Kishor's Jan Suraaj Party last year after quitting the BJP.
Charges invoked
Police have booked the accused under Sections 356, 352 and 296 of the Bharatiya Nyaya Sanhita (BNS), along with Section 67 of the Information Technology Act.
An investigation into the allegations is underway.
E20 fuel debate
The FIR comes amid an ongoing public debate over the Centre's rollout of E20 fuel, a blend comprising 20 per cent ethanol and 80 per cent petrol.
Gadkari has been one of the government's strongest proponents of ethanol blending, arguing that it will reduce India's dependence on imported crude oil, lower carbon emissions and create additional income opportunities for farmers by increasing demand for crops such as sugarcane.
However, the policy has drawn criticism from some motorists, automobile enthusiasts and social media influencers, who claim that E20 fuel may reduce fuel efficiency and could adversely affect older vehicles that are not designed to run on higher ethanol blends.
The Centre has consistently maintained that E20 fuel is safe for compatible vehicles and is a key component of India's long-term energy transition strategy.
According to the complaint, the allegations against Kashyap and the three other influencers relate to content they published on social media during this ongoing debate.