Generation I BAS General Motors introduced a BAS hybrid system in the 2007
Saturn Vue Green Line. The BAS is in the 2008–2009
Chevrolet Malibu Hybrid. It operates on the same principle as Toyota's THS-M using a 36-volt electrical system (at 42–45 volts). According to the EPA, the 2009 Saturn Vue BAS hybrid garners an improvement of 32% city (19>25mpg) and 24% highway (26>32mpg) making the combined economy improvement 27% (22>28mpg) over the base 4-cylinder FWD version. The system is reasonably simple and inexpensive, making BAS equipped vehicles some of the least expensive hybrids available. Vehicles with the BAS system use a conventional
4T45-E automatic transmission which has been modified to include a more efficient final-drive ratio and includes an electrically driven pump to provide pressure in auto-stop mode. The
air conditioning compressor continues to be operated through a belt-driven pulley, but for fuel economy improvement it can be disabled in auto-stop mode if the "ECO" A/C mode has been selected by the operator.
Cobasys, which supplies the BAS system's battery pack, had to conduct a recall in 2008 due to apparent internal
leakage of the battery modules. Citing supplier issues and slow sales, GM relegated the 2010 model year BAS hybrids to "fleet only" status.
Generation II BAS (eAssist) At the
LA Auto Show, on November 15, 2010, General Motors announced that it would be releasing an all-new version of the BAS system available in the 2012
Buick LaCrosse. While still a Belted Alternator Starter system, the system is named eAssist and includes a larger more powerful Hitachi-supplied 115-volt lithium-ion battery and a motor-generator that delivers of torque. The additional power provided by the more powerful battery and motor provides the ability to contribute more power, and more often able to electrically start and assist the 2.4L engine. The eAssist system also includes a specially modified
GM 6T40 6-speed automatic FWD transaxle.
Generation III (BAS3) A third generation was introduced in the 2016
Chevrolet Silverado/GMC Sierra and can improve fuel efficiency by about 13%. This adds about to the total weight of the truck but provides an additional and . The eAssist system includes a modified
GM 8L90 automatic transmission. It uses the same battery cells from the
Chevrolet Malibu Hybrid and the software is a modified version of the
Chevrolet Volt's. ==Other names==