• Nov 17th 2010 at 9:58PM
  • 35
2012 Buick LaCrosse eAssist – Click above for high-res image gallery

Full-size luxury sedans are typically guilty pleasures since they can be either coddling, comfort machines or all-out speed freaks. One thing they haven't been is fuel efficient... until now. Making its debut at the 2010 LA Auto Show is the 2012 Buick LaCrosse eAssist.

Power for the LaCrosse eAssist is provided by a 2.4-liter four-cylinder gasoline engine with direct-injection. It gains an efficiency boost through the addition of a 115V lithium-ion battery pack, which allows the fuel system to take a nap during certain conditions. These two power systems working together, along with the six-speed automatic transmission, allow the Buick LaCrosse eAssist to achieve 25 miles per gallon in the city and 37 mpg on the highway – a 25% percent improvement compared to the 2.4-liter flying solo. Consider this the reinvention of GM's long lost mild hybrid system.

Pricing for the 2012 Buick LaCrosse eAssist is expected to start around $30,000. What's more, the hybrid system will be fitted standard to all LaCrosse models equipped with the 2.4-liter Ecotec engine. More green luxury information is sprouting just after the jump.

2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist
  • 2012 Buick LaCrosse eAssist

Photos copyright ©2010 Drew Philips / AOL

[Source: General Motors]
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• The eAssist "smart electrification" system produces 25-percent increase in fuel economy
• eAssist technology is standard on all 2012 models with the 2.4L four-cylinder engine
• Provides customers with a full-size luxury sedan featuring 37 mpg highway and 25 mpg city for about $30,000 (exact pricing has not yet been set)
• Boost in fuel economy comes with no compromises in the driving experience

LOS ANGELES – Buick unveils the 2012 LaCrosse with eAssist,™ a new fuel-saving technology that increases fuel economy by 25 percent compared to the four-cylinder/six-speed powertrain in the 2011 LaCrosse. The eAssist technology provides class-leading highway fuel economy of 37 mpg, while maintaining the luxury, performance and value expected from Buick's flagship sedan.

The eAssist system becomes the standard powertrain on LaCrosse starting next summer. The system uses a state-of-the-art lithium-ion battery system and electric motor-generator to enable regenerative braking capability to improve LaCrosse fuel economy by an estimated 25 percent.

"The LaCrosse with eAssist technology is the latest example of how this successful car – with sales up more than 200 percent for the year – is shaking up the segment and reinventing Buick," said John Schwegman, vice president of Buick marketing. "It is the smart choice for those who want great fuel economy and performance in a luxury vehicle, with excellent value – the LaCrosse with eAssist will cost thousands less than competitors with similar technologies."

Mated to a 2.4L Ecotec direct injection four-cylinder engine and next-generation six-speed automatic transmission, the eAssist system uses power stored in the battery to provide needed electrical boost in various driving scenarios, optimizing engine and transmission operation. An advanced 115V lithium-ion battery and latest-generation 15-kW motor-generator unit help increase fuel economy through:

• Regenerative braking, which provides up to 15 kW of electricity to charge the battery
• Providing up to 11 kW (15 hp) of electric power assistance during acceleration
• Automatic engine shut-off when the vehicle is stopped
• Aggressive fuel cut-off during deceleration down to zero vehicle speed, enabled by the torque smoothing provided by the motor-generator unit
• Intelligent charge/discharge of the high-voltage battery.

Buick LaCrosse with eAssist technology also features improved underbody aerodynamics and tires optimized for performance and fuel economy, as well as active control of front-end airflow that improves aerodynamics and engine warm-up. Electronically controlled shutters in the lower grille close at higher speeds to push more air over the vehicle, which increases aerodynamic efficiency to enhance fuel economy. All of these technologies increase the eAssist system's regenerative braking capability, while also improving the vehicle's efficiency while driving.

"LaCrosse was the first in its segment with a four-cylinder/six-speed powertrain, the first with HiPer Strut and is now is leading the way with the new standard eAssist technology," said Schwegman. "Importantly, LaCrosse with eAssist is the standard powertrain for four-cylinder-equipped models and there isn't a cost premium."

LaCrosse with eAssist includes an ECO gauge on the instrument panel that continuously responds to driving behavior, enabling the driver to drive with maximum efficiency. It also features a hill-assist system that captures brake pressure to help the driver more comfortably accelerate from a stop on a moderate or steep grade. It does this by greatly reducing the tendency of the vehicle to roll backward with the engine in shut-down mode.

eAssist details

While the eAssist system shares the same basic belt-alternator-starter configuration of previous BAS designs, it delivers more than three times the power and is much more capable than the previous-generation BAS system.

"The eAssist system is more than just the next-generation BAS system. The ability to integrate regenerative braking with the latest lithium-ion battery technology creates a system that delivers significant fuel-efficiency gains that customers will enjoy," said Steve Poulos, global chief engineer of the eAssist system. "Being able to provide electric boost to the powertrain system during heavy acceleration and grade driving enables the LaCrosse transmission to operate more efficiently, while the added functionality of engine start-stop and fuel shut-off during deceleration provides added fuel savings."

The eAssist system's 115V air-cooled lithium-ion battery bolsters the 2.4L Ecotec four-cylinder engine with approximately 11 kW (15 horsepower) of electric power assist during heavy acceleration and 15 kW of regenerative braking power. That compares with only 2 kW of power assist and 5 kW of regenerative power on the previous BAS system. The greater power capability enables greater energy capture during regenerative braking for improved fuel economy.

The system also enables the Ecotec engine to shut down fuel delivery in certain deceleration conditions, which saves additional fuel. While in fuel shut-off mode, the motor-generator unit continues spinning along with the engine to provide immediate and smooth 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 smooth stop – properly positioned for a smooth restart.

"The battery system is designed to provide power assistance to the internal combustion engine, rather than storing energy for all-electric propulsion," said Poulos. "It's really an extension of the conventional internal combustion engine, not a replacement for it."

The eAssist power pack contains the lithium-ion battery pack, the integrated power inverter and 12V power supply. It is located in a compartment between the rear seat and trunk; and it is surprisingly compact and lightweight, weighing only about 65 pounds (29 kg). It still allows rear access to the trunk via the split-folding rear seat – an attribute not shared with other hybrid competitors. Trunk space is slightly reduced when compared with 2011 models with the four-cylinder/six-speed powertrain, but still offers 10.9 cubic feet (307 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 fans are designed to be quiet from the cabin.

The eAssist system's electric motor-generator is mounted to the engine in place of the alternator to provide both motor assist and electric-generating functions through a new engine belt-drive system. The motor-generator is a high-performance, compact induction motor that is liquid-cooled for increased performance and efficiency.

Next-generation six-speed

The eAssist system works with LaCrosse's direct injected 2.4L Ecotec four-cylinder and next-generation six-speed automatic powertrain combination. In the LaCrosse with eAssist, the engine is rated at approximately 180 horsepower (134 kW) and the next-generation Hydra-Matic 6T40 takes transmission technology to the next level with features designed to enhance powertrain efficiency.

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 capability of providing some electric assistance at cruising speeds allows the driver to accelerate lightly or ascend mild grades without the transmission downshifting.

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. That keeps the transmission ready to perform when the driver accelerates, for a seamless, uncompromised driving experience.
"It's a very integrated powertrain system, with no compromises in driving performance, shift quality or ride and handling," said Daryl Wilson, LaCrosse lead development engineer. "We believe this combination points to the future of vehicles powered primarily by an internal combustion engine."




2012 LaCrosse with eAssist technology

Body style / driveline:

front-drive, front-engine, four-door, five- passenger sedan



EPA vehicle class:

midsize sedan

Manufacturing location:

Kansas City, Kan.

Key competitors:

Acura TL, Lincoln MKZ, Lexus ES350



Ecotec 2.4L DOHC I-4

Displacement (cu in / cc):

145 / 2384

Bore & stroke (in / mm):

3.46 x 3.85 / 88 x 98

Block material:

precision sand cast aluminum

Cylinder head material:

SPM cast aluminum


overhead camshafts, four-valves per cylinder, continuous variable valve timing for intake and exhaust

Ignition system:

individual coil-on-plug

Fuel delivery:

direct injection and electronic throttle control

Compression ratio:


Horsepower (hp / kW @ rpm):

182 / 136 @ 6700 rpm*

Torque (lb.-ft. / Nm @ rpm):

172 / 233 @ 4900 rpm*

Recommended fuel:

regular unleaded

Emissions controls:

close-coupled, catalytic converter; variable valve timing; positive crankcase ventilation evaporative system

Estimated fuel economy (city / hwy):

25 / 37



Hydra-Matic 6T40 six-speed automatic

Gear ratios: (:1):















Final drive ratio:


Electric Drive System


belt-driven, liquid-cooled motor/generator unit and lithium-ion battery system; air-cooled power electronics and battery pack

Maximum electric generating power

15 kW @ 1570-3180 rpm

Maximum electric motor torque (cranking)

110 lb.-ft. / 150 Nm

Maximum electric motor torque (electric assist)

79 lb.-ft. / 107 Nm @ 1,000 rpm

Maximum electric motor power (electric assist)

15 hp / 11.2 kW @ 1,000-2,200 rpm

Lithium-ion battery

115V, 0.5-kWh, 15 kW peak power


Suspension (front):

MacPherson strut coil-over-spring; twin-tube dampers with gas-charged valving; hollow direct-acting stabilizer bar

Suspension (rear):


Steering type:

electric variable-ratio, rack-and-pinion

Steering ratio:


Steering wheel turns, lock-to-lock:


Turning circle (ft / m):

38.8 / 11.75



split, dual-circuit four-wheel-disc with power assist

Rotor diameter x thickness (in / mm):

front: 12.6 x 1.2 / 321 x 30 (vented)

rear: 12.4 x 0.9 / 315 x 23 (solid)

Total swept area (cu in / mm):



Wheel size and type:

17-inch steel with cover


P245/50R17 all-season blackwall


Wheelbase (in / mm):

111.7 / 2837

Overall length (in / mm):

197 / 5003

Overall width (in / mm):

73.1 / 1858

Overall height (in / mm):

59.2 / 1503

Track (in / mm):

front: 61.7 / 1567

rear: 62 / 1576

Curb weight (lb / kg):

3835 / 1739


Seating capacity:

5 (2 front / 3 rear)

Headroom (in / mm):

front: 38 / 965

rear: 37.3 / 948

Legroom (in / mm):

front: 41.7 / 1058

rear: 40.5 / 1029

Shoulder room (in / mm):

front: 57.4 / 1459

rear: 56 / 1423

Hip room (in / mm):

front: 55.2 / 1402

rear: 53.9 / 1368


EPA interior volume (cu ft / L):

99 / 2805

Passenger volume (cu ft / L):

101.7 / 2878

Cargo volume (cu ft / L):

10.9 / 307

Trailer towing maximum (lb / kg):


Fuel capacity (gal / L):

15.7 / 59.4

Engine oil (qt / L):

5 / 4.7

Cooling system ( qt / L):


*SAE certified.

Note: Information shown is current at time of publication.

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    • 1 Second Ago
      • 4 Years Ago
      Sorry trolls this is a big deal and trying to put a Sonata in the same class as a Lacrosse is just plain st.... well you know.
      • 4 Years Ago
      With recent mileage improvements (+1/+1), the US-badged Euro Accord gets a whopping 22/31 mpg.

      That's a whopping 20% worse fuel economy than the 2012 LaCrosse, despite being 10% lighter, narrower, and a foot shorter.

      And the Euro Accord with the 6MT? It has even worse mileage than the 5AT.

      Honda may have been great, but right now, the LaCrosse easily does better.
      • 4 Years Ago
      I wouldn't consider the LaCrosse's 111.7 inch wheelbase a "full size" car. The S class and 7 series' 1210-125" wheelbases is full size these days. The LaCrosse is a mid-size car.
        • 4 Years Ago
        that should be 120-125" wheelbase for the German cars.
      • 4 Years Ago
      Wow, 25/37 and about 210HP for no extra cost over the base model.

      People will complain about anything apparently.
        • 4 Years Ago
        To be fair, it's not like they made hybrids cheaper, they just decided not to offer a 4-cylinder only version of the car. So it's hard to know exactly how much you're paying for the battery pack.

        That said, 37mpg highway is really impressive for something this big. You couldn't even get that in a compact car more than 5 years ago.
        • 4 Years Ago
        Most all vehicles have enough power for steady state cruising at 60 mph/1500rpm.
        Now factor in: air conditioning, grade, headwind and the car with 40mph per 1K versus 30mph per 1K has no reserve [full engine power at 2,000 is about 57hp; 1500-38hp], so either-the torque converter will have to unlock, or the transmission downshift.
        Buick is trying to avoid both of those by drawing heavily on its electric motor.
        That is fine, that is their decision, but those who actually drive (likely not the actual customers of this vehicle) will not find the small increase in highway mileage worth the reduction in vehicle performance. (and the omission of spare wheel/jack hardware)
        and with modern VVT on both camshafts (&direct injection), you really aren't loosing highway mileage. 2,500/75mph or 2,000/80mph isn't worlds apart
        and then GM should be thinking about a 7 speed double clutch transmission to replace their transverse 6 speed autos (they should be long dead/buried by 2015)
        • 4 Years Ago
        @Mike: If the Buick has the torque to cruise at 60 mph while turning only 1500 rpm, why shouldn't they do so?

        My E60 (and SVX) turns only 2k at 60 mph / 3k at 90.
        • 4 Years Ago
        What I meant is that they aren't offering a 4-cylinder ONLY (non-hybrid) version of the car. Need more coffee.
      • 4 Years Ago
      25mpg city/37mpg hwy is not at all bad for this size of a Buick. I'd bet in certain real world condition, making it to 40mpg hwy is quite possible...
      • 4 Years Ago

      FYI the Sonata/Optima get 35 MPG highway.

      And they aren't as big/heavy as this Buick.
      • 4 Years Ago
      Well done,GM.
      • 4 Years Ago
      Is this essentially what they were doing with Saturn a few years back with mild hybrids? Was that a success? Is GM learning anything? Despite its recent turnaround (did it have anywhere to go but up?) GM has had a series of questionable moves of late. I'd say this is one of them.
        • 4 Years Ago
        The took out the spare wheel.
      • 4 Years Ago
      No, Honda has already made the gearing of the 5 speed automatic as tall as the gearing of the 6 speed auto will be.
      So there will be no increase in mileage for Honda moving to a 6 speed auto.
      It will be faster.
      • 4 Years Ago
      Considering that the SonataOptima can get 24/34, which is 1 less in town (4% difference) and 3 less on the highway (8% difference), for significantly less money, I'd say that this is just even more electrical crap that can screw up.

      I was expecting a MUCH bigger boost in the city. If this hybrid system could remotely get close to 30 mpg, I would be more impressed.

      While I disagree with the idiot that posted above me 99% of the time, he has a point.

      Buy a Honda renown for its reliability with roughly the same fuel economy as this Buick, or the car that has no known history.
      • 4 Years Ago
      eAssist, heh? More like Mild Hybrid.

      eAssist sounds like some OnStar package.
      • 4 Years Ago
      Many of you compare are comparing the fuel economy numbers to the Optima, Sonata and Accord. What you fail to realize is how heavy this car is, nearly or at 2 tons compared to 3500 lbs or so for the others. Not to mention you are comparing a luxury car that compares to a Lexus to a pedestrian Kia and Hyundia......
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