GM to Re-Introduce Mild Hybrids in Late 2011

By Dennis Haak

Remember the ads a few years ago in which GM bragged about offering more hybrid models than any other automaker?  Those not in tune with GM’s hybrid offerings at the time may have been impressed, even surprised to hear that a company known for gas-guzzling SUVs and large cars would have so many hybrids on offer.

The truth was, however, that aside from the slow-selling two-mode hybrid system installed in full-size trucks and SUVs (Silverado, Sierra, Yukon, Tahoe, and Escalade), the only other hybrid offerings GM had at the time featured the company’s so-called BAS (belt-alternator-starter) system, which was a mild hybrid system that coupled an electric motor in a start-stop like system, that was also capable of providing modest levels of propulsion assist.  GM’s former BAS system was unable to propel a vehicle solely on electrical power, as full hybrids like the Toyota Camry and Prius and Ford Escape and Fusion are able to.

Unfortunately, GM’s BAS system was so mild that it was unable to show any worthwhile fuel economy gain in some applications.  For example, the 2008 Chevrolet Malibu Hybrid was rated at 24 mpg city/32 mpg highway, while its non-hybrid counterpart equipped with a similar 2.4 liter four cylinder and a six-speed automatic was rated at 22/32.  In other words, the hybrid only gave two miles per gallon on the city cycle, and showed zero benefit on the highway.  The 2011 Malibu four cylinder is rated at 22/33, so actually tops the former hybrid model’s highway efficiency.  Of note is that GM tweaked the Malibu’s hybrid system for 2009 to give slightly better numbers (26/34), giving an overall four mile per gallon economy advantage over the four cylinder/six-speed combination.

With the closure of the Saturn brand in 2009, two of the three BAS hybrid models that GM sold in the US, the Vue Green Line and Aura Green Line, disappeared, leaving only the Malibu Hybrid to carry the BAS banner.  Accordingly, GM pulled the 2010 Malibu Hybrid from its retail lineup, though the car continued to be available to fleet buyers only.  GM also offered a mild hybrid version of the Buick LaCrosse (the previous-generation car, not the new-for-2010 model) in China.

At this year’s Management Briefing Seminars in Traverse City, Michigan, GM’s executive director of hybrid and electric powertrain engineering, Larry Nitz, announced that the company would be re-introducing the mild hybrid system in the third quarter of 2011, or about a year from now.  It would make its way into at least one midsize sedan in North America and at least one in China.

GM had announced back in 2008, pre-bankruptcy, that it had developed an enhanced version of the BAS system, to be uncreatively called BAS-II.  BAS-II was to have a lithium-ion battery (with more power and more storage capacity) and a more powerful electric motor.  We are likely finally seeing the production of BAS-II after a lengthy delay.

At the time that GM had developed its complex two-mode hybrid system, it developed two variants – one for rear wheel drive-based applications (which is in production in the aforementioned full-size trucks) and one for front wheel drive-based applications.  The front-wheel drive two mode hybrid system was to have been installed in a Saturn Vue, but Saturn’s death put those plans on ice.  You may also recall that shortly after exiting bankruptcy, GM tried to trot out a Buick two-row crossover that was really just a Saturn Vue with a Buick grille, and less than two weeks later, after receiving “consistent negative feedback,” GM reversed course and decided not to sell the Buick Vue.

So GM still has a two-mode hybrid system that was engineered to work on the Theta platform, which the Vue, Equinox, and Terrain share, but no place to put it.  At the time that the Buick Vue was pronounced dead, speculation was that this system may find its way into a future Equinox hybrid.  However, with Equinox demand so strong that its plant is running on three shifts and still not making enough to keep up with demand, I’m sure that an extension of the Equinox lineup is not at the top of the company’s priority list.

We’re looking forward to a drive in the vitamin-fortified BAS-II hybrid when it arrives next year, and eager to see some hopefully dramatic fuel economy improvements on the window sticker when they hit the market.  The Volt’s “230 miles per gallon” isn’t necessary, but a 40+ number would be good to see.