How many times does a hummingbird flap its wings per second

He can increase his visual sensitivity by looking at the signs out of the side of his eye (using rods) instead of focusing directly on them (using cones).

ROD cells are found in the eye and are any of the cylindrical photoreceptor cells in the retina that function in dim light levels.

CONE cells are found in the eyes and are any of the photoreceptor cells in the retina that are responsible for colour vision in relatively bright light.

From the definition, using the rods is the most beneficial as they function best in dim light levels. Since John drives at night, he should employ the use of his side of his eye which involves the rods for better sight.