GM finally takes a green view
2007 Saturn SUV boasts hybrid system
Sunday, January 08, 2006
Christopher Jensen
Plain Dealer Auto Editor
Phoenix- It is a little badge, but it is a really big deal.
It says "Hybrid" and it is stuck on the rear of the 2007 Saturn Vue Green Line Hybrid, marking the first real hybrid from the world's largest automaker.
When it goes on sale this summer, the Green Line model will not only offer better fuel economy but it will be quicker than the regular Vue, said Bob Reuter, General Motors Corp.'s global chief engineer for compact crossover vehicles.
Plus, GM officials say the hybrid will be priced at less than $23,000 - about $2,000 more than a conventional Vue.
The other hybrid SUV that competes most directly with the Vue would be the Escape Hybrid, which costs about $4,000 more than a conventional and comparably equipped Escape.
"We've got a combination of fuel economy, performance and price," said Reuter.
Like other hybrids, the Vue uses an electric motor to boost the engine. The batteries are recharged automatically as the vehicle is driven. It never needs to be plugged in. When the vehicle stops, the engine turns off. The signal to automatically restart comes when the driver releases the brake.
A real hybrid
General Motors sells what it calls a "hybrid" version of its full-size pickups, the Chevrolet Silverado and the GMC Sierra. However, the fuel savings in those comes from the engine shutting off when the pickup comes to a halt. There is no significant assistance from an electric motor.
An official for the Union of Concerned Scientists has called GM's "hybrid" a "laudable use of conventional technology" but not a true hybrid.
Given the chance, GM officials would doubtless argue all day that the pickups are hybrids. But it is hard to imagine there will be any dispute from anybody about the hybrid status of the Vue Green Line.
It will be assembled in Spring Hill, Tenn., but the nickel-metal hydride batteries will come from a Cobasys plant in Springboro, Ohio, near Dayton.
To the casual observer, the Vue Green Line doesn't look any different from its predecessor. But to help improve fuel economy, it has low-rolling-resistance tires and there was some aerodynamic fiddling, including lowering the ride height about an inch and adding a rear spoiler.
In addition, the suspension has been retuned to handle the different tires and about 120 pounds of additional weight.
There is also no loss of cargo space, but the spare tire is gone, replaced by batteries. There is a patch-and-repair kit with an inflator.
Inside there is no extensive, graphic display that shows fuel economy or whether power is flowing from the engine, electric motor, or both. That would have required redesigning the instrument panel, an expensive chore that would have undercut Saturn's efforts to make the Green Line affordable.
Instead there is a lonely gauge. When the needle flicks to the right, the electric motor is helping out. When it flicks to the left, the batteries are being recharged. There is also an "Eco" light. When it is illuminated, the Vue Green Line is beating the mileage estimated by the Environmental Protection Agency. But it doesn't read out the mileage.
Those figures have yet to be approved by the EPA, but GM engineers said they are figuring 27 miles per gallon in the city and 32 mpg highway. That compares with 22 mpg city and 27 highway for the regular Vue with the four-cylinder, front-wheel drive and an automatic.
Consumers should be able to get that fuel economy in real-world driving, said Larry Nitz, executive director of global hybrid powertrain.
Faster than normal
In addition, the Green Line should go from zero to 60 mph in 10.2 seconds, about one second faster than the regular Vue, Reuter said.
The reason it is quicker, despite the extra weight, is that the Green Line gets a more powerful engine. Instead of the standard 143-horsepower 2.2 liter four-cylinder, GM chose to use a 2.4 liter four-cylinder rated at 170 horsepower at 6,600 revolutions per minute and 162 foot-pounds of torque at 4,400 rpm on 87-octane fuel.
Some other automakers have chosen to go with smaller engines and use the electric motor to provide the occasional extra boost. But Saturn engineers said the more powerful 2.4 liter four-cylinder was chosen because it helped the performance of the vehicle. Since it was more sophisticated and efficient, it also allowed some other changes that made it a good, fuel-efficient choice.
It works with a four-speed automatic transmission modified for hybrid use.
Nitz said the hybrid system is cheaper because it is simpler than what competitors use. He said the work was done entirely by GM, where engineers started the project in 1996. That is an extraordinarily long gestation period.
All the software controlling the system was done by GM. Parts purchased from outside suppliers were created to GM specifications. These include batteries from Cobasys and the electric motor and generator from Hitachi.
The Vue Green Line is what would generally be considered a "mild" hybrid because the electric motor isn't strong enough to move the vehicle more than a few feet on its own. Instead, it provides about 5 horsepower and a full 115 foot-pounds of additional torque when the vehicle is starting out or if extra power is needed under way.
Vehicles such as the Escape and Toyota Prius, Highlander and RX 400h are often described as "strong" or "full" hybrids because those electric motors are strong enough to move the vehicle at low speeds for a few miles without any help from the gas engine. They are also likely to be far more expensive.
The dreaded anomaly
How did it all work? Well, a test drive of a prototype here had mixed results.
At first the hybrid system on the model that another reporter and I drove didn't work. There was no assistance from the system. A GM engineer riding with us said it was an "anomaly." As best I can figure an "anomaly" is like a screw-up without the pejorative aspect.
But the engineer said there was a software fix to be installed later that would cure it long before the vehicles go on sale this summer. Short term, we needed to stop the vehicle, turn it off and wait at least 30 seconds.
That worked. Under way, the Vue Green Line drove pretty much like a regular vehicle, with more than adequate acceleration even with four adults on board. The power flow and recharging of the batteries were seamless enough that most passengers would never know about the propulsion play taking place between the four-cylinder, electric motor and generator.
While the anomaly was embarrassing for GM officials, such problems aren't unusual in prototypes, vehicles that aren't yet at the production stage. Another colleague drove an early Toyota RAV4 recently and it persisted in flashing the traction-control light even when the vehicle wasn't moving.
Nitz said GM hasn't decided on the warranty yet, but it will probably be competitive with other hybrids. That would put it in the range of eight years or 100,000 miles.
There's no reason to think GM won't have performed an anomaly-ectomy long before the Vue Green Line goes on sale this summer. I'll drive a production vehicle closer to the on-sale date, but it looks like GM's major problem with the Vue Green Line could be building enough of them.
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