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Stop-Start Systems Improve MPG

by Ron CoganAugust 18, 2012
Stop-start systems are a virtually universal feature of hybrid electric vehicles all over the world. They are an integral part of hybrid powertrain strategies because they work well in increasing a car’s fuel efficiency in urban driving that often involves stop-and-go traffic, when a car is standing still and running at idle. Now stop-start features […]

Stop-start systems are a virtually universal feature of hybrid electric vehicles all over the world. They are an integral part of hybrid powertrain strategies because they work well in increasing a car’s fuel efficiency in urban driving that often involves stop-and-go traffic, when a car is standing still and running at idle.

Now stop-start features are migrating beyond hybrids to conventional vehicles. As one example, the new 2013 Ford Fusion is the first non-hybrid, midsize sedan that can be ordered with the automaker’s Auto Start-Stop system. As with other similar systems, when the Fusion comes to a stop the engine automatically switches off to conserve fuel. Remove your foot from the brake pedal and the engine restarts and is ready to go by the time the accelerator pedal is pressed.

How important is this? In the scheme of things, widespread deployment of such systems in new car models of all types could save more fuel than you’d think. In fact, a study by the U.S. Treasury Department estimates that congestion consumed an extra 1.9 billion gallons of fuel last year alone. That’s about five percent of all fuel used in the U.S. in 2011. Any measures that can decrease fuel burned during periods of congestion are worth pursuing.

This is especially true if there’s a solid cost-benefit case to be made. That’s happening at Ford with its Auto Start-Stop feature that’s being made available as a $295 option on 1.6-liter EcoBoost-powered Fusions sold in the U.S. The automaker says that Auto Start-Stop improves fuel efficiency by about 3.5 percent overall, although those who drive mainly in city traffic can save up to 10 percent. Ford points out it’s possible for drivers who step up to its optional Auto Start-Stop system to save as much as $1100 over five years at today’s fuel prices when compared to midsize competitors. As an environmental benefit, there are no smog-forming exhaust emissions or CO2 greenhouse gases being generated while the engine is shut down in stopped traffic. Anything that can be done to decrease vehicle emissions in urban areas is a good thing.

Besides EcoBoost engines with Auto Start-Stop, Fusions feature other fuel saving technologies like electric power steering that eliminates the engine-driven hydraulic pump, lines, and fluid. There are also six-speed transmissions enabling engines to run more efficiently by always selecting the best gear for top fuel economy.

For 2013 Fusion models, consumers can choose from five fuel-efficient powertrains. Ford’s ‘Power of Choice’ program includes two EcoBoost-powered gasoline engines with up to 37 mpg, a normally-aspirated four-cylinder engine, the Fusion Hybrid with a projected 47 mpg, and the Fusion Energi plug-in hybrid delivering up to 100 MPGe (miles-per-gallon equivalent).