Bosch: Achieving 78 Mpg

The combination of lightweight materials, improved aerodynamics and engine boosting systems will result in vehicles attaining 78 mpg.

The combination of lightweight materials, improved aerodynamics and engine boosting systems will result in vehicles attaining 78 mpg.

The maximum efficiency of the internal combustion engine has yet to reach its full potential, according to experts at Bosch Automotive Group ( "In a few years, a standard series car will be available in the compact to midsize range that can drive 78 miles on one U.S. gallon of fuel," says Rolf Leonhard, executive vice president of engineering for diesel systems at Bosch, who admits that the biggest challenge facing OEMs is reducing vehicle weight, while complying with ever-increasing regulations. Leonhard predicts vehicles will maintain an average weight of 2,645 lb., comparable to today's vehicles, although CO2 emissions will be cut to an average of 70 g/km, a sharp decline from the 182 g/km average today.

Several commonly known technologies will play a key role in achieving these "green" targets, including direct injection, turbocharging, downsizing, and improved combustion. Leonhard says Bosch engineers have developed a comprehensive set of technologies using a 1.1-liter gasoline-powered engine with turbocharging with performance comparable to a 100-kW, 2-liter engine. The key breakthrough here, he says, is the ability to boost turbo pressure to 2.4 bar, which improves power output. Maintaining that level of boost requires significant upgrades to the valve control systems: "We need more elaborate valve control that will not only control the valve timing, but also the valve lift itself and the intake diameter also needs to be varied," he says.

Another key piece of the technology puzzle needed to achieve the 78 mpg result is homogeneous charge compression ignition, commonly known as HCCI, which Leonhard says could improve the fuel efficiency of gasoline engines by 2 to 3%. He predicts HCCI will be available for mass production in 2015.

Diesel engine systems also offer additional benefits when it comes to meeting "green" targets. Bosch engineers are working diligently to achieve marked improvements to optimize the diesel combustion process through the increased use of re-circulated exhaust-gas, increased injection pressures beyond 2,000 bar, combined with start-stop systems and improved thermal management. Using these technologies, Bosch has managed to cut diesel engine CO2 emissions by 22% when compared to conventional diesel engines today, and by upwards of 45% when compared to gasoline engine systems.

"In our test bays, our efforts to advance the internal combustion engine are resulting in new engine concepts that will be ready for market by 2015," Leonhard says, adding that the critical point will be that whatever engine solution meets the environmental targets, all will have to perform at levels equal to today's engines.

Bosch’s Bohr Sees Stronger Supply Base

When the turmoil that has gripped the global auto industry begins to recede later this year, it’s likely suppliers are going to be stronger and more influential when it comes to leverage with their OEM customers, according to Bernd Bohr, chairman of Bosch Automotive Group. “The industry is consolidating, so the expectation is that those who survive—and Bosch will survive—will be better off than they were before having to compete with some very weak and half-dying suppliers who influenced the market because someone who is fighting for life is forced to do things which are very unlogical in the medium- and long-term and that impacts everyone in the business,” Bohr says.

Bohr worries, however, that the man-power cutbacks made by OEMs could have a longer term negative impact in that suppliers will have to rebuild relationships with new people, some of whom are not familiar with individual supplier’s capabilities: “In some areas you lose experience and you lose your interface. In the end, business is done by people who know and trust each other.”