 HEVs can be initially more expensive (the so-called "hybrid premium") than pure fossil-fuel-based ICE vehicles, due to extra batteries, more electronics and in some cases other design considerations (although battery renting can be used to reach the cost parity).The trade-off between higher initial cost (also called showroom costs) and lower fuel costs (difference often referred to as the payback period) is dependent on usage – miles traveled, or hours of operation, fuel costs, and in some cases, government subsidies.Traditional economy vehicles may result in a lower direct cost for many users (before consideration of any externality).