Chevrolet’s prototype hybrid S3X SUV—shown at the Paris Motor Show (earlier post)—is a diesel micro-hybrid. The prototype combines the new GM-Daewoo diesel engine with GM’s Belt Alternator Starter (BAS) system to provide stop-start functionality and regenerative braking.

The BAS system enables early fuel cutoff to the engine during deceleration and shuts off the engine at “idle”. Regenerative braking and optimized charging combined with a 36V battery further enhance fuel economy while maintaining all vehicle accessories and passenger comfort systems during the periods when the engine is temporarily shut off.

GM’s BAS system will become a common component across many of GM’s platforms. (Although this is not the system used in the micro-hybrid Sierra/Silverado pickups; those use a Flywheel Alternator Starter mechanism.) GM-Daewoo engineers adapted the BAS system for the S3X. The combination of engine management with the electric motor/generator yields up to 12% improvement in fuel economy compared to the conventional power trains—which is right in the specified design range for these BAS systems.

[A note on naming. GM calls these “mild” hybrids. Under the system we’re using (A Short Field Guide to Hybrids)—which is also the one to which Ford adheres—the vehicles featuring only the BAS hybrid systems are micro-hybrids, as they provide no additional power for propulsion.]

As mentioned in the first post, the S3X will be the first diesel-powered Chevrolet in Europe. The 2.0 liter diesel, to be manufactured at the new GM-Daewoo engine plant in Korea, will be one of the first engines resulting from the licensing agreement between GM and VM Motori earlier this year.

VM Motori, 51% owned by Penske Corp. and 49% by DaimlerChrysler, specializes in the development and manufacture of automotive diesels for vehicles such as SUVs. In 1999, VM Motori also struck a licensing deal with Hyundai for then state-of-the-art 1.5 and 2.0L diesels. Under the licensing terms, as explained in Automotive Intelligence, Hyundai can manufacture the engines only to power its vehicles, while VM is free to grant other license agreements also in Korea—as with GM Daewoo.

The GM Daewoo agreement [...] concerns basically the same engine family licensed to Hyundai but with appropriate upgrades and adaptations to suit the specific vehicle needs.

The 1.5 and 2.0L engines for GM Daewoo incorporate the latest technology features developed over the last five years; since the Hyundai license was granted. One of the most interesting upgrades is the introduction of a variable geometry turbocharger (VGT) which allows a significant increase in power output (the 2.0L engine is rated at 150 hp) whilst at the same time, in conjunction with the latest 1,600 bar common rail components, lowering engine emissions thus enabling the more stringent EU.4 exhaust emission levels to be met. Furthermore, the engines will be tuned to optimize the characteristics and requirements of each vehicle application.

VM diesels were selected after evaluation of similar engines available on the marketplace. GM Powertrain will contribute to the new project with the supply of other key driveline components.

In short, the diesel in the S3X should be a powerful but fuel-efficient performer. The addition of the BAS system, although providing a small, incremental improvement in fuel consumption, will at least be working with a more fuel-efficient platform as a base.