Fuel efficiency

Traditionally, litres per mil were used in Norway and Sweden, but both have aligned to the EU standard of L/100 km.

Kinetic energy which would otherwise be lost to heat during braking is recaptured as electrical power to improve fuel efficiency.

The larger batteries in these vehicles power the car's electronics, allowing the engine to shut off and avoid prolonged idling.

Technological advances in efficiency may be offset by a change in buying habits with a propensity to heavier vehicles that are less fuel-efficient.

Driver behavior can affect fuel economy; maneuvers such as sudden acceleration and heavy braking waste energy.

[13] Simple things such as keeping tires properly inflated, having a vehicle well-maintained and avoiding idling can dramatically improve fuel efficiency.

[14] Careful use of acceleration and deceleration and especially limiting use of high speeds helps efficiency.

Pollution produced from centralised generation of electricity is emitted at a distant power station, rather than "on site".

This was reflected in a study by AEA Technology between a Eurostar train and airline journeys between London and Paris, which showed the trains on average emitting 10 times less CO2, per passenger, than planes, helped in part by French nuclear generation.

Powered either through chemical reactions in a fuel cell that create electricity to drive very efficient electrical motors or by directly burning hydrogen in a combustion engine (near identically to a natural gas vehicle, and similarly compatible with both natural gas and gasoline); these vehicles promise to have near-zero pollution from the tailpipe (exhaust pipe).

Potentially the atmospheric pollution could be minimal, provided the hydrogen is made by electrolysis using electricity from non-polluting sources such as solar, wind or hydroelectricity or nuclear.

In 2004, a consortium of major auto-makers — BMW, General Motors, Honda, Toyota and Volkswagen/Audi — came up with "Top Tier Detergent Gasoline Standard" to gasoline brands in the US and Canada that meet their minimum standards for detergent content[17] and do not contain metallic additives.

Top Tier gasoline contains higher levels of detergent additives in order to prevent the build-up of deposits (typically, on fuel injector and intake valve) known to reduce fuel economy and engine performance.

The National Aeronautics and Space Administration (NASA) has investigated fuel consumption in microgravity.

In microgravity or zero gravity, such as an environment in outer space, convection no longer occurs, and the flame becomes spherical, with a tendency to become more blue and more efficient.

There are several possible explanations for this difference, of which the most likely one given is the hypothesis that the temperature is evenly distributed enough that soot is not formed and complete combustion occurs., National Aeronautics and Space Administration, April 2005.

Premixed flames in microgravity burn at a much slower rate and more efficiently than even a candle on Earth, and last much longer.

Trucks' share of US vehicles produced, has tripled since 1975. Though vehicle fuel efficiency has increased within each category, the overall trend toward less efficient types of vehicles has offset some of the benefits of greater fuel economy and reduction in carbon dioxide emissions. [ 5 ] Without the shift towards SUVs, energy use per unit distance could have fallen 30% more than it did from 2010 to 2022. [ 6 ]
Fuel consumption monitor from a 2006 Honda Airwave . The displayed fuel economy is 18.1 km/L (5.5 L/100 km; 43 mpg ‑US ).
A Briggs and Stratton Flyer from 1916. Originally an experiment in creating a fuel-saving automobile in the United States, the vehicle weighed only 135 lb (61.2 kg) and was an adaptation of a small gasoline engine originally designed to power a bicycle. [ 12 ]