FLAT ROCK, MI – Less than 5% of U.S. vehicles today employ fuel-saving stop/start systems, but that figure will skyrocket to 50% within four years, a Robert Bosch North America executive says at a media event at the supplier’s test track here.

Prodding the market for the emerging technology, which already exists on more than half of all new passenger cars in Europe, is a corporate average fuel economy standard that requires all U.S. automotive fleets to achieve 35.5 mpg (6.6 L/100 km) by 2016 and 54.5 mpg (4.3 L/100 km) by 2025.

“A lot of new-car programs are being quoted with standard stop/start onboard,” Scott Dahl, Bosch’s North American regional president-starter motors and generators, tells WardsAuto.

Bosch entered the segment in 2007, joining Valeo, Continental and Denso, and has since produced some 5 million systems, says Ulrich Muehleisen, head of marketing and product management for Bosch’s stop/start unit in North America.

“I think in 10 years every car will have it,” he says.

The device shuts down the engine at stop lights while the vehicle idles and restarts it as soon as the driver takes his foot off the brake or pushes in the clutch when using a manual transmission.

Fuel savings in city driving can be as high as 8% based on the European driving cycle, Muehleisen says.

But Bosch is working on a new stop/start system that will shut down the engine earlier, for instance, when the foot is taken off the gas and the vehicle is coasting. Early tests suggest this more active system can boost fuel savings from the standard 8% to as high as 15%, Dahl says.

Europe will receive this next-generation device in 2015 or 2016, and North America is expected to get it the following year, Muehleisen says.

Helping grow the stop/start market is the technology’s inclusion in several high-performance German sports cars from Porsche, BMW and Mercedes-Benz within the past few years.

A Mercedes spokesman says 11 of the brand’s 12 vehicle nameplates in the U.S. offer stop/start integrated with either 6-, 8- or 12-cyl. engines. Three versions of the E-Class come with the system.

Of the 19 Mercedes vehicles with stop/start, 10 hail from the AMG performance brand, which suggests at least some customers wanting high performance also are interested in fuel economy.

Bosch identifies these enabling technologies for stop/start:

  • Starter motor designed to be compact and durable and with improved starting performance.
  • Modified engine control unit allowing for quick response.
  • Electronic battery sensor to monitor state of charge and ensure the engine stops only if the battery has enough stored energy to restart the engine quickly.
  • DC/DC converter to guarantee proper voltage for devices such as radio and navigation.
  • High-efficiency alternator to ensure optimal battery charging for maximum number of stop/start cycles.

Muehleisen says growth in the stop/start market reflects more than wishful thinking on the part of suppliers of the technology. Repeated studies have found consumers willing to pay extra for the fuel-saving device.

The price is coming down as well. The new Ford Fusion offers stop/start optional for a mere $295, he says.

This week’s Bosch Car Clinic was the first media event for the supplier’s new North American president, Mike Mansuetti.

The event also updated Bosch’s latest offerings for gasoline and diesel engines, electronics, multimedia and chassis control systems.

tmurphy@wardsauto.com