• Nov 15th 2010 at 3:00AM
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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]
Show full PR text

• 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
      This is great news for Buick, but GM really has to find a good way to market this technology.

      It sounds like they are not using the term "hybrid" to sell this option, and I think that is not a smart move. Most people might not really understand how hybrids work (even people that call themselves "car guys"), but it is a term that consumers are familiar with as a gas-saving technology.

      Just like how Ford has turned something as common as turbocharging into a brand name with their EcoBoost label, GM really needs to up their marketing creativity and tell people about this eAssist technology.
        • 4 Years Ago
        My father, who is in the Buick wheelhouse, age-wise, sees hybrids as foreign and thought they were inconvenient because they don't just use regular gas.

        So I think maybe not using hybrid in the name is an interesting idea. Clearly they should call it a hybrid in the marketing materials, since it is one, but that doesn't mean you have to put it in the name.
        • 4 Years Ago
        It depends on whether this is something that will resonate with the customer. Remember the Northstar engine campaign?

        That was a fantastic campaign supporting something that the customer hardly ever sees.

        If GM does the same with "eAssist", they'll do very well.
        • 4 Years Ago
        GM clearly has thought the marketing through here.

        It's not a foreign Prius "hybrid"
        It's an all-American Buick with electric assist.

        Very clever splitting of the hair. And I'll bet if you drove the two back-to-back, the cars would feel completely different in how they work.
      • 4 Years Ago
      GM was way ahead of the curve with their mild BAS hybrids. People rejected them and they were sales disasters.

      Then other manufacturers do similar things (M-B and to a lesser extent BMW) and now GM comes back with an improved version.

      I wish them better luck this time. Using an up-to-date transmission and minimizing the cost increase will go a long way toward improving acceptance I think.

      The press release would imply this car doesn't have a lead-acid battery, but instead creates 12V from the Lion pack. It would be ironic if this is were the case, given the Leaf has a 12V lead-acid battery under the hood.
        • 4 Years Ago
        By the time those leaking batteries came around, the fate of the BAS hybrids had already been sealed. Gas prices were very high and people were snapping up the ultra-high mileage hybrids and scoffing at the lower end ones. I would think much of GM's low production was in response to low sales.

        The BAS hybrids could have been executed a lot better, that's for sure. But mostly people just looked at the mpg and said why bother. Because the old BAS hybrids were leashed to an outdated 4-speed auto, you could get the Malibu hybrid with 26/34 or get the regular 4-banger on a 6-speed and get 22/33. People just didn't see why they would give up trunk space, pay extra for a hybrid and potentially have to replace the battery later to get barely increased mpg.
        • 4 Years Ago
        I think spin cycle is right on this one. Most of the arm chair critics scoffed at the original BAS claims of being a hybrid because of the inevitable comparisons to the prius, etc. They simply laughed it away even though it had the shortest time periods for return on investment. This is a MUCH smarter strategy because polls always suggested people were open to hybrids they just didn't want to pay more for them. This is a great first step towards that end.
        • 4 Years Ago
        @spin cycle: I agree with everything you wrote.

        GM won't be calling any of their cars "hybrids" for the foreseeable future because "hybrid" = Pious.

        But I'll bet we'll see a lot of eAssist come out on larger vehicles precisely because it works and makes a huge bump on mileage where GM would normally get hurt badly. Also, those vehicles are inherently expensive enough that GM can bury the cost of the system.

        I wouldn't be surprised at all to see this feature made standard on every Enclave, Escalade, and Yukon within the next 5 years.
        • 4 Years Ago
        People rejected them because they just weren't very good, and the cars often had funky issues related to the hybrid powertrain. And production was held up by leaking batteries from their supplier: http://www.autoblog.com/2008/06/03/doh-battery-leakage-hurts-gm-hybrid-production/ so they didn't make as many early on as they had planned. And leaking batteries (even if caught before installation) didn't really help instill much faith in consumers anyway.
      • 4 Years Ago
      Yet another sign that shows that, as unfortunate as it would appear at surface, (or if you listen to them whine) Government Mandates are the only way the large corporations will bring technological advances.

      This one's a win for Engineers.
      • 4 Years Ago
      Didn't the older Chevrolet 4 cylinder hybrid get something like 22/34 mpg? And that was with a mere 4 speed auto. I personally liked this car and was looking fwd to the 6 speed edition and then it was canned.
      Is there an improvement on the non hyrbid LaCrosse in terms of acceleration?

      Why not put it on the 6 cylinder model as well?
      • 4 Years Ago
      Definitely a step in the right direction - a practical, cost-effective application of hybrid technology that has a meaningful benefit. Step 1, accomplished.

      Step 2: Let's see this with AWD. No one has yet offered a hybrid car (excluding crossovers and SUVs) with AWD, as if there wasn't a market for one. Whoever is first to market with such a vehicle will get my business, and I'm sure many others'.

      The AWD system used on the LaCrosse (including it's torque vectoring rear differential) adds exactly 170lbs to a CXL, and has NO fuel economy penalty (both are 17/27).

      Even if there was a marginal hit on the hybrid, lets assume 1mpg city/2mpg highway, we are talking about an AWD vehicle that would get 24/35. Far better than anything else on the market.
        • 4 Years Ago
        There is no torque vectoring differential.
        • 4 Years Ago
        Not true - I agree that Buick's own website does not seem to do a good job of highlighting this (interestingly, they refer to it as a "locking rear differential" on the specs page of the Buick site), but it's there. I've read this in a number of places. They use the same Haldex differential that they used on the Saab 9-3 and new 9-5. They also use that on the Cadillac SRX.
      • 3 Years Ago
      Bad news if you want to use the trunk...it takes up over 30% or more of the trunk space and then you have to eventually replace the battery if you want to keep the car. 1/3 trunk space gone....for a little better gas mileage...not me!
      • 4 Years Ago
      I would also like to commend GM for keeping the weight in check. The LaCrosse was already a little overweight, but if the specs are accurate, the hybrid will carry a 6 POUND weight penalty over the existing 4-cylinder LaCrosse! No doubt helped by using the Lithium Ion pack for the 12-volt system - I assume this means they were able to drop the heavy lead-acid battery, which may have completely offset the Lithium pack.
        • 4 Years Ago
        Presumably, Buick got lead-acid battery out, along with the starter & alternator, and replaced them with the battery pack and motor/generator.

        Keeping the weight penalty of the extra batteries below 6 lbs is a good job.
      • 4 Years Ago
      Good achievement would love to get a buick Lacross but the car is way to big IMO iirc its curb weight is around4000 lbs.
      • 4 Years Ago
      You'd think that after taking up all that trunk space for the battery, they could at least spring for multilink trunk hinges to gain the space back.
        • 4 Years Ago
        The Chinese prefer the "C" type hinges found on the LaCrosse to the multilink type hinges found on the Malibu. Since the Chinese market buys four times the number of Buicks than are sold in the US, the design decision is obvious.
      • 4 Years Ago
      Given modern technology using electric motors inside the transmission, I donno why every vehicle doesn't come as a hybrid in at least one version or another. Not saying every car sold should be a hybrid, but it ought to be simple enough to create a hybrid version of most road-going vehicles that are being produced today. With new emissions standards, it would be in a manufacturer's best interest to do so, if nothing else just to pad their average emissions ratings...
        • 4 Years Ago
        Not all electric motors used in hybrid applications fit into existing transmissions. I think GM is somewhat unique in this application. Is this how Hyundai does it?

        • 4 Years Ago
        @ rudukai13

        I have been saying that for quite some time now.

        At some point in time - and I think it's sooner, rather than later - all cars will have at least one hybrid trim level on sale. The cost to add hybrid components onto almost any car are dropping, with the potential to have some decent benefits.

        Give it ~5-10 years and it will be just like how it is nearly impossible to buy a car today without power locks or windows, or without power-assisted steering. It is going to be something that pretty much all cars have built in.

        The sooner one of the car makers realize that, the better. I fully believe that GM should lead the pack and make Buick their hybrid-only division. If Ford kept Mercury around, I think they should have done the same thing with them.
      • 4 Years Ago
      so there won't be any non hybrid versions of the 4l?
        • 4 Years Ago
        Nope, this replaces the base powertrain...
        • 4 Years Ago
        well, i guess the lacrosse will no longer start nearly as much as the regal eh?
      • 4 Years Ago
      Wife's averaging just over 30 MPG with her V6 LaCrosse. 20 in town. Respectable enough to keep vs moving to this engine option. I still do not feel 100% comfortable with all this start-stop technology out there
        • 4 Years Ago
        what was the American car from 20 years ago with start stop tech?
        • 4 Years Ago
        Start-stop has been used in Europe for many, many years now, so I assume manufacturers have got it very well integrated.
        Our US EPA fuel economy test standards don't include the kinds of activity where start-stop benefits, but it's supposed to be a real-world useful addition for in-town driving.
        The Euro economy testing does benefit from it, which is why they've been incorporating it for years.
        The full press release suggests that they don't actually stop turning the engine, they just cut off the fuel, and the mutant alternator continues to spin the engine. This means they wouldn't have to use an electrically driven A/C compressor, among other things, although they do mention an electric pump for the transmission to keep the fluids moving.
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