Overinflating of tires can actually cause a vehicle to use more energy. It decreases the rolling resistance coefficient but can increase the frictional loses of the tire under torque or braking action. For optimal efficiency you need to find the right balance.
Resistance is also felt from frictional loses in the powertrain. Bearings, differential, gearing, clutches all offer a resistance to the car. Some people don't consider this a rolling resistance but in a sense it is a resistance to the rolling motion of the car.