Gas-guzzler

Gas-guzzler commonly refers to a vehicle that consumes fuel inefficiently.

The term originally came into use in the US when congress established Gas Guzzler Tax provisions in the Energy Tax Act of 1978 to discourage the production and purchase of fuel-inefficient vehicles. The gas guzzler tax had applied only to cars (not trucks) and was collected by the IRS.

Today the term is often used to refer to SUVs or other semi-large vehicles that qualify as "light trucks". Nevertheless the term extends to all fuel-inefficient vehicles, from antiquated V8 American classics to Italian-bred sports cars. A Lamborghini Murciélago, a Plymouth Roadrunner, and a Hummer H2 might all be classified as gas-guzzlers, though they are very different cars.

Common examples
Common examples of 'gas-guzzlers' include:
 * PSVs:
 * Pickup trucks
 * SUVs
 * Full-size vans
 * High performance sports cars
 * Classic muscle cars
 * Some luxury cars.
 * Most old cars can be regarded to have bad fuel economy, North American models averaging between 9 mpg-US (26 L/100 km; 11 mpg-imp) - 19 mpg-US  (12 L/100 km; 23 mpg-imp) when compared to similar modern vehicles.

Reasons for bad fuel economy
There are several reasons for bad fuel economy in all of the cars mentioned:
 * Large displacement engines. A large displacement engine generally requires more fuel to run it than a smaller engine.
 * Small displacement engines. An excessively small engine often requires more fuel to run than a moderately bigger engine which can deliver more power per piston bore than its smaller equivalent. A smaller engine has to burn more fuel to produce power similar to a larger bore engine, thus causing the mean fuel economy to go down under normal operating conditions. This situation is often found in Ireland where a motor taxation system is used which taxes cars based on engine capacity.
 * Heavy weight. A heavy vehicle requires more work to accelerate than a lighter vehicle, requiring more powerful (larger displacement) engine with higher fuel consumption to achieve a similar power-to-weight ratio.
 * Large drag coefficient. A less aerodynamic vehicle must deflect a greater volume of air when moving at the same speed than a more aerodynamic one. To overcome this drag, a more powerful engine with higher fuel consumption is needed.

Most SUVs and large pickup trucks share several of the qualities needed to be inefficient, making the light truck market with their added popularity very criticizable for causing decreased fuel efficiency. Most passenger cars are usually affected by only one or two of these factors. For instance, sports cars usually have only a large displacement engine.

Gas-guzzlers in work use
Much of the environmentalist opposition to gas guzzlers is not directly aimed at any model in particular, but rather at its use. Indeed the use of heavy duty vehicles such as SUVs and pickup trucks for construction, forestry, or any professional use that requires it is generally considered less objectionable than their use as a family car. However, some models are purpose-built, or modified in a way that renders them useless as work vehicles (such as lowered off-road vehicles, delicate and expensive upholstery on a SUV...).

Means to decrease fuel consumption
The increasing trend is to make engines smaller yet more efficient. For example, removing a V8 and replacing it with a supercharged V6 results in much better fuel economy without compromising on power or ability. This trend is mainly caused by the declining popularity of fuel inefficient vehicles due to rising gas prices.

Then there is the reduction of vehicle weight, with a switch to monocoque construction instead of body on frame construction and an increased use of lightweight materials, aluminium, plastics and high strength HSLA steels instead of ordinary mild carbon steel.

Gas-guzzlers are not only seeing a scale back in engine size and weight but also in the type of fuel used to power it to prevent environmental damage caused by the use of fossil fuels. For example, some light truck manufacturers are adopting hydrogen fuel technology in order to provide the consumer a vehicle with a much lower running cost. The problem with these alternative fuel technologies is that they are either too expensive for widespread use and/or they are scarcely available especially in smaller countries.

Diesel technology is widespread in light trucks, especially in Japan and Europe. The bad reputation of diesel fuel and the previously bad quality of the fuel, however, have led to the rarity of such vehicles in the U.S market. The excessive particle emissions of diesel engines have also been cut back with particulate filters, which are offered for most modern diesel engines. The introduction of ultra-low sulfur diesel fuel in the U.S. along with rising gas prices might make diesel-powered vehicles popular again in the United States.

Driving habits and vehicle maintenance are easy to change and can have a big impact on fuel efficiency. Driving at 120 km/h (75 mph) can consume 25% more fuel than cruising at 100 km/h (60 mph) since automobiles are optimized to run in the 60-100 km/h (40-60 mph) range. Sudden acceleration, poorly maintained vehicles (frequency of oil changes and brand) and gasoline brands can also impact overall fuel efficiency by over 20%.

Basics
The U.S government introduced the Gas Guzzler Tax as a part of the Energy Tax Act. The tax was introduced to tax the purchase of inefficient vehicles at the same time that Corporate Average Fuel Economy (CAFE) standards were introduced. The Gas Guzzler Tax applies only to vehicles classified as cars, as opposed to light trucks. Since 1991, cars with a combined fuel economy rating under 22.5 mpg-US (10.5 L/100 km; 27.0 mpg-imp) miles per gallon have been subject to the tax. Light trucks, which includes virtually all sport-utility vehicles, pickup trucks and vans, are not subject to the tax.

Criticism
The primary criticism of the tax is that it does not apply to light trucks. As a result, relatively few vehicles are subject to the tax. When the tax was first introduced, light trucks were viewed as primarily work related vehicles. With the shift towards consumer uses for SUVs and pickups, the original rationale for exempting trucks is considered invalid by critics of the current tax law.