.

Flexible Fuel Vehicles

Wikicars, a place to share your automotive knowledge
Jump to navigationJump to search

A flexible-fuel vehicle or dual-fuel vehicle is an automobile that can typically alternate between two sources of fuel. A common example is a vehicle that can accept gasoline mixed with varying levels of ethanol (gasohol). Some cars carry a natural gas tank and one can switch from gasoline to gas.

Flexible-fuel vehicles in the United States

North American vehicles from approximately 1980 onward can run on 10% ethanol/90% gasoline (e.g., E10) with no modifications. Prior to 1980, many cars imported into the United States contained rubber, aluminium, and other materials that were generally non-compatible with any ethanol in their fuel delivery systems, and these cars experienced problems when E10 was first introduced.Cars made in the US from the late 1970's onward can run on E10 with no modifications. E10 fuel is widely available. Going beyond 10% ethanol generally requires special engineering.

In the United States, many flexible-fuel vehicles can accept up to 85% ethanol (E85) or up to 85% methanol (M85). The fuel mixture is automatically detected by one or more sensors, and once detected, the ECU tunes the timing of spark plugs and fuel injectors so that the fuel will burn cleanly in the vehicle's internal combustion engine. Originally, sensors in both the fuel-line and in the exhaust system were used for flexible fuel vehicles. In recent years, manufacturers have instead opted to use only sensors in the exhaust manifold, before the catalytic converter, and to eliminate the fuel inline sensor. As E85 and M85 are more corrosive, special fuel system materials are also required. Some manufacturers also require a special motor oil be used, particularly in vehicles using methanol fuel.

In 1993 through 1995, Chrysler offered M85 flexible-fuel versions of the Dodge Spirit and Plymouth Acclaim with an MPFI 2.5 L 4-cylinder engine. FFV Chrysler minivans were also offered beginning around the same time, with a version of the corporate 3.3 L V6 enigne. In 1998, General Motors Corporation introduced their first light truck (an S10, with 2.2L engine) in a flexible-fuel configuration. In 1999, Ford Motor Company introduced a flexible-fuel option on its Ford Ranger pickup trucks, and it has also been an option on the company's Taurus model. Other manufacturers such as Mercedes-Benz also offer E85/Flexible fuel vehicles. Flexible fuel vehicles are often identified as such by exterior badging. They can also be identified by labelling adjacent to the fuel filler and fuel gauge, and by the engine identifier digit in the VIN.

As of 2005, most existing vehicles that are available to the public with flex-fuel engines are sport-utility vehicles or others in the "light truck" class. Sedans, wagons, and others are usually only available in flexible-fuel configurations as part of fleet vehicle purchases by companies. Starting in 2006, though, more widespread availability is planned for standard models intended for non-fleet sales.

A 1988 federal law provides an incentive for creating flexible fuel vehicles in the form of credits that can be used to relax Corporate Average Fuel Economy fuel efficiency standards. It is alleged that this efficiency relaxation has decreased overall US fleet efficiency, thereby resulting in increased nationwide fuel consumption.[1]

Over 4 million flexible-fuel vehicles are currently operated on the road in America, although a 2002 study found that less than 1% of fuel consumed by these vehicles is E85[2].

List of currently-produced flexible fuel vehicles

Europe

USA

See also