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.

MORE: Five Things You Need To Know About Stop-Start Systems

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.

Have you used a car with automatic stop-start before? Share your experiences below.


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