Vehicle weight influences the size and cost of a system's guideways, which are in turn a major part of the capital cost of the system. Larger vehicles are more expensive to produce, require larger and more expensive guideways, and use more energy to start and stop. If vehicles are too large, point-to-point routing also becomes more expensive. Against this, smaller vehicles have more surface area per passenger (thus have higher total air resistance which dominates the energy cost of keeping vehicles moving at speed), and larger motors are generally more efficient than smaller ones.