YOKOHAMA, Japan -- When the redesigned Honda Fit arrives in U.S. showrooms in the middle of next year, it won't have an engine stop-start system.
One reason is that cars with stop-start can be a drag to drive.
The fuel-saving technology, which shuts off the engine at stoplights, is popular outside North America. In Japan it comes standard on all versions of Honda's new Fit small car.
But the lag between stop and start makes it slow off the line. And that is partly why engineers chose not to use it in the United States.
Nobuhiko Shishido, a lead powertrain engineer for the new Fit, said that in the United States, where speed and power rule, stop-start systems mean small cars will be left in the dust.
They "will lose at stoplights to V-6s," Shishido said at a recent Fit preview. He was referring to the extra split second it takes to re-engage the engine when a stop-start vehicle gets ready to roll again.
With stop-start, the technology automatically shifts the car into neutral to turn off the engine. Then when the driver lifts off the brake pedal, the starter motor re-engages the engine and the drivetrain is shifted back into drive. The whole process can take nearly a second, said Kentaro Yokoo, chief engineer of the hybrid drivetrain in the Fit.
That can be an eternity when priming to bolt from a stoplight.
Hybrid cars use stop-start because it improves fuel economy. But the hefty electric motors they use to help propel the car do double duty to restart the engine. They are so big and powerful that the startup is almost seamless.
Nonhybrids must rely on the run-of-the-mill starter motor, which is usually too weak for a seamless reboot, Yokoo said. Engineers can get around that by increasing the size of the starter motor, but that adds weight and cost.
There also is a marketing problem because the EPA's fuel economy testing cycle doesn't give extra credit to stop-start systems. So even though their real-world performance is better than their official mpg rating, they are a hard sell.
And stop-start has other idiosyncrasies. For example, the air conditioner compressor turns off during the stop phase. While the system continues to blow cool air, it's not quite as cool as full-blown air conditioning.
Electric power steering is disengaged, making it harder to reposition the wheels during a stop. And an engine restart sometimes shakes the steering wheel.
Most drivers get acclimated to stop-start quickly, Yokoo said. But in the United States there might be a steep learning curve.
