• 23
2012 Buick LaCrosse eAssist technology – Click above for high-res image gallery

Think of this as a Buick LaCrosse Hybrid. General Motors' new eAssist technology employs a 115-volt lithium-ion battery and 15-kilowatt electric motor to increase fuel economy by 25 percent compared to today's four-cylinder LaCrosse. This means the Buick sedan will achieve an estimated 25/37 miles per gallon (city/highway).

2012 Buick LaCrosse eAssistDuring initial acceleration, the electric motor delivers 15 horsepower and 79 pound-feet of torque to get the LaCrosse moving. A torque-smoothing function is activated as the gasoline engine is turned on, and the eAssist system kicks back on during deceleration, using a fuel shut-off feature and regenerative braking, combined with a start/stop system for the 2.4-liter gasoline engine. At full tilt, the gas engine produces 182 hp and 172 lb-ft of twist to keep things moving along at speed, and is mated to GM's Hydra-Matic 6T40 six-speed automatic transmission.

Other modifications to the LaCrosse eAssist include improved underbody panels and an active front air-flow shutter to keep the sedan's coefficient of drag as low as possible. Inside, a revised instrument panel not only shows when the LaCrosse is operating in electric mode, but has an eco-meter for the driver to monitor how efficient his or her driving style is.

GM will be offering eAssist as standard equipment on all 2012 Buick LaCrosses equipped with the 2.4-liter four, and pricing is expected to begin around $30,000. Considering the LaCrosses's size, level of content and efficiency, it sounds like quite a bargain. Read the full details in GM's press release, 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

[Source: General Motors]


• 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

I'm reporting this comment as:

Reported comments and users are reviewed by Autoblog staff 24 hours a day, seven days a week to determine whether they violate Community Guideline. Accounts are penalized for Community Guidelines violations and serious or repeated violations can lead to account termination.

    • 1 Second Ago
      • 4 Years Ago
      For a mid-size car it sure seems like a big old thing! But 25/37 are pretty decent numbers. They keep boasting about the cD being pretty good, did I miss it somewhere? I am curious to see both the cD and the frontal area. But Buick is building pretty decent cars, if you need a large car, you could probably do worse. I hope they keep it close to the low end of the 2010 Lacrosses range of MSRP's. They went from $26.2k to $33k. If they market this thing under $29k it will be a winner.
      • 4 Years Ago
      Give em a break all. These are impressive numbers. This system also greatly improves the quality of the ride. This is a vastly impoved IMA or BAS at a reduced price. Much less NVH, start stop is awesome and you can't beat torque. More HP is for rednecks in HEMI's, torque rules on the road. AND they called a spade a spade and didn't call it a "Hybrid". eAssist, I like it. It explains the system completely in one word.
      • 4 Years Ago
      Ha, 27mpg city out of a 4 cylinder hybrid, that's sad.

      This could actually be worse than the German hybrids.
        • 4 Years Ago
        And this is a hybrid-lite. with tall gearing, only goes 135mph (best case) in 4th gear. and weighs over 3800 lbs.
        • 4 Years Ago
        Only 138mph! pathetic!
        • 4 Years Ago
        GM took the oil cooler off the 2.4 a couple of years ago, I don't know if they put it back for the direct injection versions.
        So that 135mph may not be sustainable. 125mph in 5th probably, 115mph in 6th certainly.
      • 4 Years Ago
      Many people consider Honda's IMA system is already hopelessly outdated, and now GM is adapting a very system? That makes GM double-out-of-date!
      • 4 Years Ago
      I'm beginning to believe Jack Rickard (evtv.me) when he says you might as well start making your own EVs because the car makers will never deliver. not because the Leaf and Volt will never come, but the price is high and the selection narrow.
      it looks like the bad automakers will try to hold on to the ICE for several years still with nonsense like this car.
      • 4 Years Ago
      nah GM doesn't do atkinson yet. I don't think you can conclude that from compression ratio.
      • 4 Years Ago
      This will be a game changer. A 25% boost in mpg for (I have read in other publications) about a $1,500-2,000 premium price. This will be a technology at a price point that consumers will embrace in huge numbers. Once this becomes standard across the entire product line, the cost premium should come down to $1,000 as economies of scale kick in.

      The analogy for this development is to look back a few years and remeber how ifrst desk top computers, and then flat screen televisions, entered the mainstream when their price came down to about $2-3,000.

      Bravo for GM!
      • 4 Years Ago
      Yawn...., little battery pack, so so mileage, big price. Question is will Goverment Motors still be in business after bankruptcy II in 5 years?
      • 4 Years Ago
      Sounds like current gen Honda IMA coming soon to the General. Great that they make it standard. Pity they can't use Ford as the benchmark instead (Ford Fusion Hybrid EPA 41 city/34)
      • 4 Years Ago
      Never mind I missed it. It is belt driven.
      • 4 Years Ago
      Compression ratio is 11.2 to 1. This indicates Atkinson cycle.
        • 4 Years Ago
        Atkinson has a longer expansion stroke, not compression stroke. High compression is usually either the province of direct injection, where the fuel is cool enough so it doesn't preignite, and/or the fuel doesn't ignite as easily as regular petrol such as ethanol or diesel.
        • 4 Years Ago
        The power output does not indicate atkinson cycle. It's DI.
      • 4 Years Ago
      Very impressive??

      In 2005 Honda Accord came with hybrid, with a V6 engine and more than 250 hp. It was not tuned for max fuel economy, but rather better performance than the standard V6. Still it had better fuel mileage than the Buick at the rate of 4mpg better in city, same hwy. All this 7 years before the Buick's planned introduction. Many people complain about Honda IMA (being a mild hybrid) and Honda lagging behind. Well, for me it seems GM is way behind,....... and belt drive???

      Specs 2005 Honda Accord Hybrid:

      o Blue Book Value: $14,750-$15,150
      o Base MPG: 29 City / 37 Highway
      o Base engine: 3.0L V6
      o Driving range: 632 miles

        • 4 Years Ago
        remind me again what the premium was on the Accord Hybrid over the 4-cylinder version -- and what are the EPA combined numbers for the I4 and V6-Hybrid?
        • 4 Years Ago
        Actually your mistaken. Those figures are the OLD EPA MPG calculations.


        These are the corrected amounts,

        25 MPG City
        33 MPG Hwy
        28 MPG Combined

        AND... It was thousands more. $3,290.00 Corrected for inflation is $3,680

        So.... Yes impressive for what is.

        • 4 Years Ago
        Actually your mistaken. Those figures are the OLD EPA MPG calculations.


        These are the corrected amounts,

        25 MPG City
        33 MPG Hwy
        28 MPG Combined

        AND... It was thousands more. $3,290.00 Corrected for inflation is $3,680

        So.... Yes impressive for what is.

    • Load More Comments