BAS (belted alternator starter) is a category of automotive parallel hybrid technology that uses an electric motor to contribute power to the internal combustion engine's crankshaft via a serpentine belt. By mounting this motor generator unit in the conventional location traditionally used for the standard automotive alternator, it permits a low-cost method of adding mild hybrid capabilities such as start-stop, power assist, and mild levels of regenerative braking. BAS systems differ from other mild hybrid systems as they are not run off the vehicle's crankshaft. Toyota In June 2001, Toyota introduced a BAS hybrid system under the Toyota Hybrid System-Mild (THS-M) brand name. It operates similarly to other mild hybrids with a start-stop system, in that it shuts down the engine as the vehicle comes to a stop and instantly restarts it when the brake pedal is released. THS-M is capable of providing modest levels of power assist during launch/acceleration and similarly modest levels of "blended" regenerative braking during deceleration. A 36-volt lead-acid battery (housed in the vehicle's trunk and operating in a 42-volt electrical system) is used to operate a permanent magnet motor/generator unit mounted to the engine in a similar fashion to a conventional alternator. Then, through a high-tension drive belt, the motor/generator unit is capable of starting or assisting the engine. A conventional 12-volt battery and starter motor are retained and used whenever the engine is cold as during initial start-up. Although unable to operate in pure all-electric EV mode, THS-M provides improvements to both city and highway fuel efficiency over non-hybrid versions of vehicles available with the system. According to Toyota, the system is designed to provide a 15% increase in fuel economy. The system is designed to be simple and easily adaptable across a wide range of vehicles, with no significant modifications required to the vehicle chassis to accommodate the system. This allows THS-M vehicles to be produced on the same assembly line as non-hybrid versions, producing substantial cost savings and allowing production to be adjusted more easily. The first production model equipped with THS-M was the eleventh generation Toyota Crown Royal Saloon Mild Hybrid, introduced in August 2001, combining the system with a 3.0 L 2JZ-FSE straight-six engine. It was followed in October 2002 by the Toyota Crown Sedan Super Deluxe Mild Hybrid, which combined the system with a 2.0 L 1G-FE engine. General Motors Generation I BAS General Motors introduced a BAS hybrid