Ford's new Flex is introducing a new mileage-extending technology that results in about a one-percent gain in overall fuel economy on its stylish, full-size crossover. The system generates this added efficiency by temporarily interrupting fuel flow to the Flex's 3.5-liter/262-horsepower V6 during periods of deceleration -- or any time a driver's foot lifts off of the accelerator pedal. That transition is automatically and seamlessly reversed whenever the vehicle reaches a low speed or the driver reaccelerates. Ford integrated this deceleration fuel shutoff engine circuitry with the vehicle's electronically controlled six-speed automatic transmission, where it keeps the V6 operating at lower revs and in a more efficient mode whenever possible. The net result is class-leading EPA ratings of 17 city/24 highway mpg.
To prevent the annoying hesitation that often accompanies this type of aggressive on/off fuel switching, Ford's powertrain gurus also developed proprietary software that defines and controls the overall parameters of the package. "The Flex's fuel management system is calibrated to operate imperceptibly to the driver," said Kevin Layden, Ford Powertrain calibration chief engineer. "It saves fuel with no fluctuation in powertrain performance or compromise in driveability." Ford plans to introduce this aggressive fuel management system on most of its upcoming product lines during the next few years.