Stop-start systems have taken much longer to infiltrate the U.S. market than they have elsewhere, but several manufacturers are finally coming around to the idea of the gas-saving technology.

One such automaker is Ford, which has announced that 70 percent of its North American vehicle lineup will be available with stop-start by 2017.

The technology has had such a slow uptake in the U.S. due to the way vehicles are measured under EPA-devised fuel economy tests.

As a comparison, the European city economy test is much shorter than its EPA counterpart--780 seconds (around 13 minutes) compared to 1874 seconds (31 minutes)--and a greater proportion of the test involves the car at rest, when stop-start systems would typically engage.

Unsurprisingly, this means stop-start systems make a much greater contribution to the European figures than they do in EPA testing--cars fitted with such systems spend much longer with the engine off than they do during the EPA process.

For any driver who regularly contends with stop-and-go traffic though, the systems can be quite effective--more so than EPA testing reflects.

Ford says average fuel savings may account for around 3.5 percent, but those who regularly drive in heavy city traffic may see up to 10 percent improvements--as well as reductions in CO2 and pollutants, and the subjective benefits of lower noise and vibration from a car not idling away in traffic.

As the technology has progressed, with beefier batteries and long-life starter motors easily capable of handling the stop-start process, the technology can now be considered a low-hanging fruit--hence Ford's adoption of it across much of its future model lineup.

The first vehicle available with the technology is Ford's 2014 Fusion with the 1.5-liter EcoBoost engine--but it's set to spread to many more vehicles.

In Europe, the tech is available virtually throughout Ford's range--including the Fiesta 1.0 EcoBoost, set to debut in the U.S. next year. Stop-start isn't yet confirmed for that model, but with 37 mpg combined economy and up to 45 mpg highway, it's among the better-performing non-hybrids on the market.


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