User talk:162.119.64.110 and Fuel economy in automobiles: Difference between pages

Fuel economy is the amount of fuel required to move a vehicle over a given distance. While the fuel efficiency of petroleum engines has improved markedly in recent decades, this does not necessarily translate into fuel economy of cars, as people in developed countries tend to buy bigger and heavier cars.

Units : distance

There are two ways to measure the fuel economy in automobiles:

• The amount of fuel used per unit distance; for example, litres per 100 kilometres (L/100 km). In this case, the lower the value, the more economic a vehicle is (the less fuel it needs to travel a certain distance);
• The distance travelled per unit volume of fuel used; for example, kilometres per litre (km/L) or miles per gallon (mpg). In this case, the higher the value, the more economic a vehicle is (the more distance it can travel with a certain volume of fuel).

To convert between mpg (imperial) and litres / 100 km, apply the formula $284/x$ where x is the mpg

Units : Carbon Emission

A further related measure is the amount of Carbon dioxide produced as a result of the combustion process. (Units: Co2 g/km) a petrol engine will produce around 2.3 kg of Carbon dioxide for each litre of petrol consumed [1], a diesel engine, 2.8Kg per litre[2] (although this appears more, a diesel vehicle typically is more economical and therefore in terms of Co2 g/km it is less than an equivalent petrol car)

Factors in fuel economy

Most energy used by automobiles does not go toward acceleration of the vehicle and is, in that sense, wasted. In a frictionless world, no energy would be lost in travel. In reality, energy is lost in many ways.

Energy usage includes

• Engine efficiency
• Aerodynamic drag
• Rolling friction
• Potential energy (hill climbing)
• Kinetic energy, which is ultimately lost to braking in the absence of regenerative braking; this is the primary cause of the difference between city mileage and highway mileage
• other friction

Ideals

• Ideally, accelerating quickly would be just as efficient as accelerating slowly, however engine efficiency varies with engine torque.

Trends in fuel economy

The choice of car and how it is driven drastically affect the fuel economy. A 'top fuel' dragster can consume 6 gallons for a 1/4 mile run i.e., 24 gallons per mile. the other extreme was set in 2003 by a team entered in the Shell Eco-marathon that was called Microjoule, from France that achieved a world record of 10,705 mpg.

Clearly both such vehicles are extremes and most people drive ordinary cars that typically achieve 15 to 25 miles per gallon. However due to environmental concerns caused by CO₂ emissions, new EU regulations are being introduced to reduce the average emissions of cars sold to 120g/km of CO₂. However as people in the western world grow wealthier they tend to want to buy higher status less efficient cars. Therefore the car manufacturers have a real problem in reconciling these two factors so as to meet these tough new emissions regulations in the future.

Several technologies are therefore being considered to try and meet these targets but they may increase the initial price of vehicles, they may reduce the overall cost of running the vehicle over it's lifetime.

Highly efficient cars such as the Toyota Prius and Audi A2 already exist along with electric ZEV (zero emission vehicles) but consumers don't seem to want to buy them in significant quantities. Therefore the issue is not so much a technological one but rather one of customer perception and consumer acceptance.

Gas Guzzler Tax

Main article: Energy Tax Act

The Energy Tax Act of 1978 in the U.S. established a gas guzzler tax on the sale of new model year vehicles whose fuel economy fails to meet certain statutory levels. The gas guzzler tax applies only to cars (not trucks) and is collected by the IRS. The purpose of the Gas Guzzler tax is to discourage the production and purchase of fuel-inefficient vehicles. The gas guzzler tax was phased in over ten years with rates increasing over time. The tax applies only to manufacturers and importers of vehicles, although presumably some or all of the tax is passed along to automobile consumers in the form of higher prices. Only new vehicles are subject to the tax, so no tax is imposed on used car sales. The tax is graduated to apply a higher tax rate for less-fuel-efficient vehicles. To determine the tax rate, manufacturers test all the vehicles at their laboratories for fuel economy. The U.S. Environmental Protection Agency confirms a portion of those tests at an EPA lab. Two separate fuel economy tests simulate city driving and highway driving. A weight average of city (55%) and highway (45%) fuel economies is used to determine the tax.

In some cases, this tax may only apply to certain variants of a given model - for example, the 2004-2006 Pontiac GTO did incur the tax when ordered with the four-speed automatic transmission, but did not incur the tax when ordered with the six-speed manual transmission.

CAFE standards

Main article: Corporate Average Fuel Economy

The Corporate Average Fuel Economy (CAFE) regulations in the United States, first enacted by Congress in 1975, were federal regulations intended to improve the average fuel economy of cars and light trucks (trucks, vans and sport utility vehicles) sold in the US in the wake of the 1973 Arab Oil Embargo. It is the sales-weighted average fuel economy, expressed in miles per gallon (mpg), of a manufacturer's fleet of current model year passenger cars or light trucks, manufactured for sale in the United States. The standards are limited to vehicles under a certain weight, but those weight classes will be expanding in 2011 if current law (as of April 2006) holds.

Fuel economy-boosting actions and technologies

• Reducing vehicle weight by using materials such as aluminum, fiberglass, plastic, high-strength steel and carbon fiber instead of steel and iron
• Designing the exterior of the vehicle to reduce aerodynamic drag
• Using lower-viscosity lubricants (engine oil, transmission fluid, axle fluid)
• Replacing incandescent light bulbs with Light Emitting Diodes to reduce power consumption
• Incorporating Locking torque converters in automatic transmissions to reduce slip and power losses in the converter
• Augmenting a downsized engine with an electric drive system and battery (hybrid vehicles)
• Automatically shutting off engine when vehicle is stopped (mild hybrid)
• Recapturing wasted energy while braking (regenerative braking)
• Optimizing other engine combustion strategies:
  • Stratified Charge combustion
  • Lean burn combustion
  • HCCI combustion
  • Variable valve timing
  • Supercharging or twincharging (when coupled with a downsized engine)

Aftermarket consumer products exist which are purported to increase fuel economy; many of these claims have been discredited.

See also

• ACEA agreement
• Electric cars
• Emission standard
• Energy conservation
• Hypermiling
• Vehicle Efficiency Initiative (Canada)

External links

Conversion

• Car Fuel Efficiency Converter.

Consumer published articles

• How to increase auto fuel efficiency
• In-depth advice to help increase fuel efficiency
• Fuel efficient driving and modifying
• Simple Guide to Increase Fuel Efficiency

Sites and pages commissioned by various governments' institutions

• US EPA Green Vehicle Guide
• US government's FuelEconomy.gov
• Canadian Energuide: Vehicles
• Green Vehicle Guide Australia
• European Community Directive 93/116/EC — European Commission Directive 93/116/EC of 17.12.1993 adapting to technical progress Council Directive 80/1268/EEC relating to the fuel consumption of motor vehicles

Additional sites and pages with fuel economy tips

• Fuel Reformulator
• FuelEconomyTips.com
• mpgresearch.com
• Gas Mileage Database
• Fatter U.S. drivers guzzle more gas, spend extra $2.8 billion annually
• Keep a track of your vehicle's gas mileage
• Metric converter
• Gas Mileage Tips
• U.S. Government Fuel Economy Site