With the advent of the 2015 Chevrolet Impala, General Motors will fully drop its eAssist mild-hybrid powertrain from the Chevy lineup. The Impala, the last Chevy to offer eAssist, next year will follow the Malibu's lead and abandon the complex, pricey system—a 2.4-liter four-cylinder paired with a lithium-ion battery and 15-kW electric motor—for simpler and cheaper engine stop-start tech.
The Impala LS and LT Eco trims–each $2000–$2275 dearer than their gas-powered LS and LT counterparts—make up fewer than 1 percent of all Impala sales–will be discontinued. Not everything eAssist is dead, however—the setup's heavier-duty starter motor and electric transmission pump carry over to the new stop-start system, just as they did in the Malibu. (The system also lives on in the Buick LaCrosse and Regal.) Also similar to the 2014 Malibu, the Impala's stop-start system will be standard on all models utilizing the base 2.5-liter four-cylinder engine.
Stop-start boosts four-cylinder Impalas' city fuel economy estimates by 1 mpg, to 22 mpg city; the highway estimate remains 31 mpg. (The Impala with eAssist, for reference was EPA-rated for 25/35 mpg.) For this mild improvement, the Impala's base price rises a negligible $65 to $27,735. The fuel-saving tech won't be available on Impala models with the 3.6-liter V-6, which GM attributed to development costs and software changes that haven't been applied beyond its 2.4-liter and 2.5-liter Ecotec engines.
General Motors didn't simply add stop-start and call it a day, however; the automaker added some clever features to ensure the operation is as seamless as possible. For example, the Impala, uses specific motor mounts to quell vibration, while stop-start's electronic brain is smart enough to keep the engine running if the car doesn't reach 6 mph—a welcome feature in crawling traffic where continuous stop-start cycles cause us to tear out hair. Like Ford, which has pledged to add stop-start systems in 70 percent of its lineup by 2017, GM said it was considering other models but wouldn't name names.
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Still, GM tells us eAssist will continue on despite its higher cost and relatively middling gains in efficiency.
"Stop-start is a simpler, less expensive technology," said GM spokesman Chad Lyons. "However, we are committed to eAssist and you will continue to see it on GM products in the future."
Lyons' sentiments back up previous hints we've received from GM employees that eAssist indeed has a future, and that in Chevrolets specifically, the setup could return in a slightly different form. Stop-start systems, typically reserved for hybrids and expensive European cars where E.U. emissions tests favor them, are only available on two other American cars, the Ford Fusion and Ram 1500. Later this year, the 2015 Chrysler 200 and 2015 Ford F-150 with the 2.7-liter EcoBoost V6 will offer the feature.
We applaud Chevy's swift moves to cancel a powertrain option few customers were choosing and replace it with a basically free (to the customer) and unobtrusive—if our experience in stop-start–equipped Malibus is anything to go by—fuel-saving add-on for the already excellent four-cylinder Impala.
from Car and Driver Blog http://ift.tt/nSHy27
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