President Obama is taking a sales pitch for his administration’s requirement that automakers nearly double the gas mileage of their cars out on the road following his acceptance of the Democratic nomination in Charlotte, N.C., this week.

Republicans have criticized the fuel efficiency requirement, arguing that it is too burdensome for car companies and will make cars too costly for consumers.

But in both his acceptance speech at the Democratic convention and his first post-convention appearance in Portsmouth, N.H., Friday, Obama forged ahead with his argument that the gas mileage standards will be both good for drivers at the pump and for the environment.