|Malibu Eco with eAssist. Click to enlarge.|
The 2013 Chevrolet Malibu Eco with eAssit (earlier post) will be the first model of the new 2013 Malibu lineup to reach dealer showrooms in North America, starting in the first quarter of 2012. The 2013 Malibu Eco is the first Chevrolet vehicle to feature eAssist, GM’s light electrification system already introduced in the Buick lineup. Along with specific aerodynamic enhancements, it achieves 12% greater highway fuel economy than current models equipped with the 2.4L engine; GM estimates highway fuel economy of 37 mpg US (6.4 L/100km).
The eAssist system consists of a 32-cell, 0.5-kW lithium-ion battery, an electric motor-generator and next-generation Hydra-Matic 6T40 six-speed transmission. The system’s electric motor-generator is mounted to an Ecotec 2.4L four-cylinder engine, in place of the alternator, to provide both motor assist and electric-generating functions through a revised engine belt-drive system. The motor-generator is a high-performance, compact induction motor that is liquid-cooled for increased performance and efficiency.
The air-cooled 115V lithium-ion battery is integrated into a power pack located in a compartment between the rear seat and trunk. The compact power pack weighs only about 65 pounds (29 kg), and allows rear access to the trunk via the split-folding rear seat. Trunk space is slightly reduced from 2011 models, but still offers 14.3 cubic feet (405 liters) of storage. An electric fan cools the power pack, drawing air from a vent located in the package tray, behind the rear seat.
The induction motor-generator bolsters the engine with approximately 11 kW (15 horsepower) of electric power assist during heavy acceleration and 15 kW of regenerative braking power. This power capability enables the battery to capture energy during regenerative braking for improved fuel economy.
e Assist technology also allows for a numerically lower 2.64 final drive ratio. Significant internal transmission changes to clutch controls and hardware provide reduced spin losses while improving shift response and time. The added electric power provided by the eAssist system allows for higher gearing to improve steady state efficiency without impacting acceleration performance or driveability. The system’s ability to provide some electric assistance at cruising speeds allows the driver to accelerate lightly or ascend mild grades without the transmission downshifting. Automatic Grade Braking keeps the transmission in a lower gear when decelerating or coasting on a downgrade, helping to improve brake wear performance.
An auxiliary, electric-driven transmission oil pump is added to the 6T40, which keeps the transmission primed and the fluid flowing when the engine shuts down at a stop.
The system also enables the Ecotec engine to shut down fuel delivery in certain deceleration conditions, which saves fuel. While in fuel shut-off mode, the motor-generator unit continues spinning along with the engine to capture regenerative braking power and provide take-off power when the driver presses on the accelerator. Then, as the vehicle comes to a stop, the motor-generator unit spins the engine, bringing it to a stop and positions it for a smooth and seamless restart.
Malibu Eco’s eAssist system is mated to an Ecotec 2.4L direct-injection four-cylinder engine and next-generation six-speed automatic transmission. The 2.4L engine features dual-overhead cams, direct injection, continuously variable intake and exhaust timing and electronic throttle control, as well as a lightweight aluminum cylinder block and cylinder head. It is rated at an estimated 182 horsepower (134 kW) and is a variant of the same engine recognized as one of Ward’s Ten Best Engines in 2010.
A power flow display in the driver information center—or the center console screen when equipped with the navigation system—indicates in which of the following modes the Malibu Eco is operating:
Battery charging: the eAssist motor is charging the high-voltage battery when the vehicle is slowing.
Electric assist: the eAssist motor is providing electric power boost to the engine.
Auto-Stop: the vehicle is stopped, the engine has automatically shut off and is ready to automatically restart when needed.
Driver-selectable modes include Eco mode, which maximizes the frequency and duration of Auto-Stop; and Comfort mode, which reduces the frequency and duration of Auto-Stop to maximize cabin comfort.
|Aerodynamic improvements. Click to enlarge.|
Engineers removed about 60 counts of wind drag from the 2013 Malibu’s design, compared to its predecessor. Malibu Eco is among the first vehicles in the midsize segment with a standard fuel-saving, active shutter system. Located in the lower grille, the Malibu Eco’s active shutter system automatically closes airflow through the lower intake opening when air intake is least needed.
When closed, the shutter system enhances aero performance by redirecting airflow around the front of the vehicle and down the sides, rather than through it. The shutter is open or closed based on engine coolant temperature and speed. For example, the shutters open when the car is traveling up a hill, pulling a trailer, or in hot city driving; the shutters close at highway speeds when less engine cooling is required.
Other aerodynamic features on the Malibu Eco include:
Dual-port grille upper is closed to redirect air flow up and over the hood;
Outside rearview mirrors designed to maximize efficiency;
Tail lamps shaped for aero performance without design penalty;
Four underbody panels cover approximately 50% of the lower portion of the vehicle and provide a cleaner airflow path beneath the vehicle.
The new Malibu is also the quietest Chevrolet yet, according to GM. To achieve that, interior engineers used road testing, sound evaluation tools and vehicle components to reduce, block and absorb noise from entering the cabin. Some of the contributors to its quiet driving experience include:
Malibu’s stiff body structure and isolated engine cradle help reduce noise and vibration from being transmitted to the interior.
The wind tunnel-tuned exterior has a low coefficient of drag; a low drag count of .30 Cd (Eco model) helps reduce wind noise to what GM expects to be a segment-best 33 decibels.
Air leakage into the passenger compartment, a primary noise source for all vehicles, is expected to be the best in the segment, at about 20-25 cubic feet per minute.
A 5.4-mm acoustic-laminate windshield and 5-mm acoustic-laminated front door glass reduce wind noise by about 3 decibels when compared to conventional tempered glass.
Sixteen expanding-foam acoustic baffles are placed strategically in cavities throughout the body structure. The foam expands when the body passes through the drying oven in the paint shop, filling the cavities to restrict or eliminate sound paths.
Liquid-applied sound deadening and melt-on sound deadening materials are used on the floor pan.
The Malibu Eco carries an MSRP of $25,995, including a $760 destination charge. The new Malibu is Chevrolet’s first global midsize sedan and will be sold in nearly 100 countries on six continents.