2012 Buick LaCrosse eAssist is nice, but mpg disappoints

— -- General Motors' 2012 Buick LaCrosse with eAssist is a reminder that GM does a lot of things right.

If you suffer from outdated "Import Good, Detroit Bad" prejudice, you can take a moment here to realign your reality.

Meantime, let's review: LaCrosse was redesigned for the 2010 model year. The eAssist mild-hybrid system is what's new for 2012. It replaces the former gas-only four-cylinder base models.

The eAssist version is priced at $30,820 including shipping, the same as the only other power offering, a V-6 gasoline engine.

That's a hefty $2,830 more than the base 2011 CX four-cylinder LaCrosse, and $270 more than the midgrade 2011 CXL four-cylinder.

In return, you get fuel-economy ratings 6 miles per gallon — 20% to 32% — better than the 2011 four-cylinder gas models.

Though the Buick has opportunities for improvement, it also is a poster car for the idea that GM makes good vehicles, thoughtfully equipped, smartly appointed, handsomely styled.

The marquee feature, eAssist, is a very mild hybrid setup. An electric motor/generator sits where the alternator normally would be. The four-cylinder gas engine turns the motor/generator via a beefed-up "fan belt." And the motor/generator can turn the engine (and, thus, help propel the car) via the same belt.

GM will use eAssist on multiple brands, including the 2013 Chevrolet Malibu coming early next year.

It seems risky to include "assist" in the name of any Buick because it implies "assisted living," and reminds one that the brand still attracts older buyers. But a plus is that the name lets your imagination pick what "e" means: Electric assist? Engine assist? Energy, ecology or economy? Yes.

The eAssist electric motor can add 15 horsepower when passing or scooting up a freeway ram. It also can propel the car alone momentarily, as when pulling away from a stoplight.

In typical hybrid fashion, the motor turns into a generator on deceleration and braking, recharging the modest-size lithium-ion battery pack in the trunk.

Also like other hybrids, the eAssist system stops the gas engine when you're at a long light or otherwise halted. The engine stays off up to two minutes. It restarts when you lift off the brake pedal.

If you creep forward electrically, you won't notice any vibration as the gas engine comes back into play. If you're stock-still, and suddenly demand lots of gas-engine power, you feel slight shudders.

LaCrosse eAssist gets much of its mileage improvement from features other than the electric motor.

For example, the system shuts off gas to the engine during deceleration and keeps it off till you stop. Most automakers shut off the gas, then restore it for smoothness as the car nears the stop. While Buick's way saves fuel, decelerating the test car sometimes produced jerks and stumbles — often enough to give pause to a potential buyer.

The eAssist models also have low-rolling-resistance tires, plus a trunk-lid air spoiler, underbody panels and other aerodynamic aids.

And the climate control has a selectable "eco" mode that lets the cabin temperature rise or fall a bit from your setting. That lets the AC compressor run less, cuts drag on the engine, saves gas.

Some of LaCrosse's other things-done-right may seem minor, but are the very things that, if executed poorly, would make you tire of a vehicle before the loan is paid. Among things done right:

•Tire-pressure monitor tells the actual pressure in each tire. Most other makers use a dumbed-down orange alert light that requires you to get out and test the pressure in each tire, which nobody bothers to do, of course.

•The reach to the turn signal lever is perfect. Some makers put it too far away, requiring you to take your hand off the wheel. And the operating feel of the stalk is smoother than in some $60,000 cars.

•Styling is curvy, and slightly showy without being a show-off. The test car's mocha color was a visual knockout.

•Bluetooth phone link connected fast and easily.

•Big, easy-to-read display screen for stereo controls, navigation, backup camera makes life easier.

Undercutting the sheen, however:

•Visibility is poor, thanks to big, swoopy roof pillars and angled back window.

•Interior door handles sacrifice function for style, are too curved and shallow, especially for big or gloved hands.

But the most disappointing fault was the tester's real-world fuel economy of about 18 miles per gallon driven conservatively in the suburbs, with plenty of gas engine auto-stop time. That's notably less than the rating of 29 mpg in combined city/highway use, which roughly approximates suburban conditions. Hard to reconcile in a mileage-meant car.

Overall, the LaCrosse is quite an appealing machine, but the eAssist, in real-world use, doesn't seem like the magic bullet.

About the LaCrosse eAssist

•What? Mild-hybrid, gas-electric drivetrain for big Buick sedan. Priced the same as the V-6 gas model, but rated 6 miles per gallon better. Front-drive, four-door, five-passenger sedan on the big end of midsize or small end of full-size.

•When? On sale since September.

•Where? Made at Kansas City, Kan.

•Why? Have you looked at federal mileage regulations lately?

•How much? Starts at $30,820 including shipping, same as the V-6 gasoline model.

•What's the competition? Buick says its Acura TL, Lincoln MKZ, Lexus ES350.

•What makes it go? 2.4-liter four-cylinder gasoline engine rated 182 horsepower at 6,700 rpm, 172 pounds-feet of torque at 4,900 and a belt-driven, liquid-cooled motor/generator rated 15 hp and 79 lbs.-ft., mated to six-speed automatic transmission.

•How big? Slightly longer, wider than Honda Accord. LaCrosse is 197 inches long, 73.1 in. wide, 59.2 in. tall on a 111.7-in. wheelbase. Weighs 3,835 lbs. Passenger space, 101.7 cu. ft. Trunk is a below-average 10.7 cu. ft. because it houses battery pack.

Turning-circle diameter, 38.3 ft curb-to-curb.

•How thirsty? Rated 25 miles per gallon in town, 36 mpg on the highway, 29 in combined driving. Test car trip computer registered 18.2 mpg (5.49 gallons per 100 miles) in easy-going suburban driving. Burns regular, holds 15.7 gal.

•Overall: Very nice car, but disappointing mileage and drivetrain refinement.

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