DETROIT -- The Chevrolet Malibu Eco, which uses General Motors' eAssist mild-hybrid system to boost fuel efficiency, is about to become a tough sell.
That's because, for the 2014 model year, the fuel economy of the pricier Eco model will be matched by that of the base-engine Malibu, thanks to a makeover aimed at sparking slow sales of the mid-sized sedan.
The Malibu's improved 2.5-liter, four-cylinder base engine could help Chevy's lagging position in the cutthroat mid-sized sedan segment. But the comparatively weak appeal of the Eco model raises questions about the effectiveness of GM's eAssist system, a mild-hybrid technology that the company plans to spread across much of its vehicle lineup.
GM is adding a standard stop-start system to the base 2.5-liter, along with other powertrain tweaks, for a 14 percent bump in its EPA rating for city driving to 25 mpg, from 22. It leaves base-engine models with the same ratings as the 2.4-liter Eco model -- 25 city and 36 on the highway. And the base Malibu has more horsepower and a cheaper sticker price by about $2,300 on a comparable trim package.
GM is betting that stronger demand for the improved base engine will far outweigh weaker Eco sales, which have accounted for less than 10 percent of sales since the redesigned Malibu was launched last year. The base Malibu's 29 mpg combined rating leapfrogs the base-model ratings of the Toyota Camry, Ford Fusion, Kia Optima and Hyundai Sonata.
The automaker hopes to reverse sliding sales with the Malibu's makeover, which also includes a roomier rear seat and new front fascia. Through August, Malibu sales sank 17 percent, to 140,463, fifth among mid-sized sedans.
GM bills eAssist as a modestly priced fuel economy package, compared to full hybrids, that produces a nice boost in mileage. The system also uses a stop-start system. But it also utilizes a lithium ion battery in the trunk, regenerative braking and a small electric motor to assist the 2.4-liter engine under heavy loads, such as when merging into highway traffic.
But advances in the efficiency of regular gasoline engines can nullify the fuel economy edge of the eAssist system, says Alan Baum, a suburban Detroit auto analyst who tracks hybrid technology. The base 2013 Nissan Altima, which has a 2.5-liter, four-cylinder engine, has a 27/38 mpg rating without use of electrification or a stop-start system.
And some full-hybrid systems offer far greater fuel efficiency for only modestly more money, Baum notes. For example, the Toyota Camry Hybrid gets 40/38 rating for $28,480, about $1,800 more than a comparably equipped Malibu Eco.
"As hybrid technology offers a better cost-benefit relationship, and as the internal combustion engine improves, does that squeeze mild hybrids and make them not really competitive?" Baum says. "That's a big question for GM going forward."
Pam Fletcher, executive chief engineer for electrified vehicles, says GM's experience with the stop-start system on eAssist models helped engineers execute the technology on the 2.5-liter Malibu. GM says that model is the first mid-sized sedan to offer stop-start as standard base model feature.