DRIVEN: First Drive: 2012 Buick LaCrosse eAssist Prototype

March 25, 2011
The Buick LaCrosse has become a strong seller for Buick since its 2009 redesign, but that hasn’t prevented Buick from making continous improvements. For 2012 comes the biggest change yet – a new fuel saving technology called eAssist. Having driven a preproduction model, we can say the gains are well worth the effort.
2012 Buick Lacrosse Eassist Rear Three Quarter View
The eAssist technology is, in essence, what some call a mild hybrid, but GM doesn’t call it a hybrid at all. You won’t see a single identifying badge on the car, and it won’t be offered in any sort of green trim package. Buy a four-cylinder 2012 LaCrosse, and you get a 25 percent improvement in fuel economy from last year’s mode, to an estimated 25 mpg city, 37 mpg highway. You’re welcome.
OK, this isn’t mere magnanimity on the part of the General. In truth, the company already tried to market this technology as a hybrid when it was offered in more primitive form on the Chevrolet Malibu and Saturn Aura. They were given shiny green “H” badges and touted as competitors to the likes of the Toyota Camry and Ford Fusion Hybrids. Consumers didn’t buy them -– literally or figuratively -- leading to their cancellation in 2009.
To GM’s credit, though, it didn’t simply give up on the technology. The eAssist system operates in the same basic way as the old Belt Alternator Starter hybrids: an electric motor/generator driven by the accessory belt captures energy from regenerative braking, which in turn powers accessories, assists during acceleration, and restarts the gas engine after stops. However, every component has evolved dramatically. The most obvious improvement is in the batteries, which are now lithium-ion rather than nickel-metal hydride and power a significantly beefier, 15-kilowatt motor. Engineers also credit several “enablers,” including a new six-speed automatic transmission that’s light-years ahead of the old system’s four-speed, and direct fuel injection, which allows the car’s computers to control ignition with much greater precision than before.
As noted, there are no badges on the LaCrosse to extol its green virtues, but close observers (really close observers) will spot a much more important exterior tweak in the lower front grille. It now has a plastic slat that opens or closes depending on vehicle speed and engine temperature to minimize drag. That’s right, active aerodynamics. On a Buick. Additional tweaks include underbody panels to further reduce drag and low rolling resistance seventeen-inch tires. The LaCrosse also went on a significant diet such that it only weighs about 10 pounds more than last year’s model despite carrying a 65-pound battery pack behind its rear seats.
2012 Buick Lacrosse Eassist Diagram
For all its new technology, the LaCrosse feels practically unchanged from behind the wheel. Drivers may notice the 20 hp of electric assistance during low-speed acceleration -– 0-to-60 mph acceleration has improved by 0.2 second from last year despite the switch to a numerically lower final drive ratio – but it’s still not fast. The sprint to sixty takes 9.2 seconds, and the 2.4-liter four-cylinder hustles to get there. As in most hybrids, the engine shuts down during full stops. Compared with older applications of start/stop technology the process is quick and smooth. The electric motor advances the pistons to the optimal ignition point and then fires up the engine within 300 milliseconds. This same process occurs even less perceptibly at speed: eAssist also allows for more aggressive fuel cutoff upon deceleration than in conventional cars, keeping the engine spinning but not combusting all the way to a stop This is decidedly different from an EV-mode -– eAssist cannot power the vehicle by itself. Neither is it “freewheeling,” where the engine disconnects from the drivetrain. Quite the contrary: the torque converter actually stays locked both to keep the belt-mounted motor/generator spinning and to smooth the startup. In most cases it’s nearly impossible to discern when the engine is running. GM hopes to make further refinements before the car hits production in June.
2012 Buick Lacrosse Eassist Front End
Otherwise, the LaCrosse provides the same good driving experience we’ve come to expect. The light steering is surprisingly crisp, and the suspension, though unapologetically tuned for comfort, keeps body motions in check. Even the brakes feel relatively progressive and strong, with only a hint of that telltale regenerative sponginess. The attractive interior remains unchanged, save for the addition of a graphic on the nav screen that monitors power flow and efficiency. It’s as useless as it is on hybrids, but at least it provides passengers some clue that you’re saving the planet.
Clever as eAssist is, its fuel economy doesn’t come close to the city figures of “full” hybrids like the Lincoln MKZ, though it enjoys a slight edge on the highway. There are a few inherent limitations in the technology, as well. The batteries are not climate controlled like those in the Chevrolet Volt and thus need time to warm up in extremely cold weather. For that reason the car retains a lead-acid battery and a traditional starter for ignition. Since the battery pack draws air for cooling from behind the package shelf, it can occasionally compete with passenger’s need to cool down the cabin as quickly as possible (we weren’t able to observe this on a 27-degree day, but engineers say the air conditioner must sometimes stay out of recirculation mode to adequately supply the battery pack with fresh air). Additionally, the need to keep the engine in gear even when it isn’t running leads to pumping losses. Engineers indicate there’s room for further improvement but caution that their goal is not to “design a system to handle every conceivable situation.”
Nevertheless, the four-cylinder LaCrosse now offers buyers an interesting alternative to the segment’s other near-luxury hybrids, the MKZ and Lexus HS250. It won’t match the city fuel economy of those models, but it’s more luxurious and better to drive.
It should also be cheaper. The LaCrosse with eAssist will start for around $30,000, some $3000 more than in 2011. That increase also accounts for trim changes that eliminate last year’s (ugly) steel sixteen-inch wheels and (cheap) manual climate controls. Buyers who don’t want eAssist will still be able to buy a LaCrosse with the 3.6-liter V-6 for the same price.
We’ll get a better idea of how much eAssist really costs when it debuts as a standalone option on the Regal later this year. GM hasn’t announced any more applications yet, but engineers say it can be integrated into a wide range of vehicles with relative ease. We hope they do so. Far from a gimmick, the eAssist system now provides GM an interesting new weapon in the ever-intensifying fuel-economy war.
2012 Buick Lacrosse Eassist Trunk

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