# Strategies for Reducing Automobile Fuel Consumption
## 5 Transportation Policies, Alternatives, and Externalities
### Fuel Consumption Standards and Their Effects  
Assessing the energy efficiency of freight and public transport vehicles, including trucks, buses, and passenger cars, requires specific _metrics_, such as passenger-kilometers (passenger-km) or ton-kilometers (ton-km) per megajoule (MJ) of _primary energy_ for passenger and cargo transport, respectively. Utilizing primary energy as a benchmark (rather than consumed liters of fuel) allows for the possibility of drawing equitable comparisons between vehicles, be they driven by electric traction or by burning petroleum derivatives. Notably, energy efficiency metrics are often contingent on _load-carrying capacities_; that is, a vehicle with high occupancy yields superior energy efficiency compared to one that is scarcely occupied. By emphasizing metrics such as passenger-kilometers and ton-kilometers per each primary energy megajoule, we can ascertain vehicular energy efficiency with precision, facilitating enlightened choices for sustainable transportation.  
Some Colombian national regulations for energy efficiency [73; 74; 75] seem to indicate that a positive energy effect can result from formulating fuel efficiency standards (and related measures) to help consumers identify and select vehicles that offer the best fuel efficiency. To achieve this, car manufacturers and dealerships should include fuel efficiency information in their catalogs. Additionally, it is advisable to use _fuel efficiency labels_ on vehicles to encourage customers to consider fuel efficiency when making a purchase [76], much like the _energy efficiency labels_ used for household appliances. By adopting fuel efficiency labeling, potential buyers can make more informed decisions when purchasing a vehicle. This labeling system enables the evaluation of future expenses and empowers users to verify if the car's performance matches the manufacturer's claims [77]. A permanent label (sticker) on each new vehicle should contain key information, such as fuel efficiency (in km/L) for city, highway, and combined driving conditions. It could also inform about the impact of the city driving efficiency on projected _economic costs_ for one year and the projected expenditure or savings over five years (compared to the average city driving efficiency of the model's segment). Moreover, the label could include the environmental impact ranking in gr/km of CO\({}_{2}\) emissions.  
Beyond the primary focus on energy optimization in road transport, it is imperative to consider other aspects of energy efficiency, such as energy expenditure during vehicle production or energy invested to extend the vehicle's lifespan [78; 79]. Distributing energy expenditures across an extended lifecycle culminates in a marked diminution of _aggregate annual vehicular energy costs_ (inclusive of fuel energy), spanning from manufacturing and maintenance to operational expenditures. An integrative perspective toward transportation promotes optimized fuel consumption and could result in an increase in service loads for freight vehicles and augmented occupancy levels for passenger cars.