There is a long history of connection between cars manufacturers and fascists, to be fair. But beyond the history involved in them, car centric design contributes to it: Mass resistance is more difficult with physical separation, which driving promotes. Inefficient use of resources promoted by spread out design, and a requirement to buy, fuel, and maintain an expensive vehicle make people in even wealthy societies poorer, and people struggling to maintain a formerly comfortable quality of life are exactly the kind of people that fascists like to recruit, as they can often be convinced to blame scapegoat groups for their struggles and yearn for older times that the fascists can promise a return to.

Im not suggesting the one is entirely to blame for the other, you can certainly have fascists without car dependence, and cars without fascists, but they contribute to the conditions that fascism can take hold in, and make life easier for such regimes once installed.