Fuel economy is a hot topic in every American household, and automakers are doing their best to re-tool their production lines to shift the focus of their newer vehicles onto more efficient designs and technologies. While it is not so difficult to create smaller vehicles which are lighter, powered by smaller engines and use less fuel, it is definitely a challenge to take more purpose-built vehicles such as pickup trucks and SUV’s and reduce their fuel consumption without compromising their utility.
There are several characteristics shared by pickup trucks that cause them to inherently use more fuel than an automobile. One of the ‘biggest’ issues is their size. Pickup trucks are heavy vehicles, partly due to their rugged frames which are required for hauling and towing, and partly due to the weight of their 4-wheel drive systems and heavy-duty suspensions. Pickup trucks are also quite large in order to have excellent cargo capacity. Larger size = more air resistance a.k.a. drag. All of that weight and aerodynamic drag requires a fair amount of horsepower to move, meaning that trucks must be equipped with larger displacement motors in order to provide to the flat, linear torque curve that is required for both daily driving and for towing.
The Tundra’s 5.7L V8 with VVT-i.
Until very recently, these engines have been known as fuel hogs, but several technologies have emerged which are changing that image. Variable-valve timing, which enables an engine to change the timing of the exhaust and intake valves on the fly in order to emphasize fuel economy or maximize horsepower, is now standard equipment in the Toyota Tundra’s 5.7 liter V8, as well as being featured in several GM and Ford pickups. Dodge and GM have outfitted their full-size trucks with cylinder management, which allows the engine to shut down half of its cylinders during normal driving in order to save fuel. GM also produces a hybrid engine system, set to go on sale in the fall of 2008, which claims to lower fuel use by as much as 40 percent in city driving conditions through the use of an electric motor. For diesel truck owners, direct-injection technology has not only increased the fuel efficiency of these engines, but it has also significantly cut their greenhouse gas emissions.
Low rolling resistance tires are also being offered on new pickup trucks (such as Ford’s new SFE F150), and while they offer a significant fuel economy benefit (anywhere from a 3% to 8% improvement), they also detract for a vehicle’s braking ability, handling, payload capability, and off-road prowess. Auto manufacturers have been traditionally reluctant to offer low-rolling resistance tires on pickups, but the fuel economy gain might be enough to offset the reduced capability for some owners.
Will truck buyer’s accept the reduced capabilities and performance of low rolling resistance tires in exchange for fuel economy gains?
Even the weight of pickup trucks is starting to be reigned in. Wherever possible, body components are being constructed out of materials such as composite carbon fiber and aluminum, which are as strong as steel but much lighter. Vehicle hoods are commonly made from aluminum, and composite pickup truck beds seem to be a near certainty in the very near future.
The aerodynamic properties of trucks are also receiving a great deal of attention. While historically the shape of a pickup truck has been boxy and upright, extensive wind tunnel testing is giving engineers and designers the ability to tweak a pickup’s body so that it produces less drag when moving through the air – allowing for better mileage.
Pickup trucks will most likely never be fuel economy champions, but given the rising costs of gasoline and diesel, manufacturers are doing their best to ensure that drivers are able to squeeze as many miles as they can out of a gallon of gas.
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