Machine Design

Scanning for Ideas: Hybrid powertrains for luxury SUVs

General Motors and Cadillac (, in a nod to upscale consumers concerned about the price of gas and the environment, have developed a hybrid powertrain for its Escalade SUV.

Edited by Stephen J. Mraz

It will boost fuel economy for city driving by 45%, giving it about 17.5 mpg. And there’s little doubt that much of the technology developed for the Escalade will percolate down to less-expensive vehicles in the future.

The Escalade carries a two-mode powertrain. It can take off from a standstill and drive at low speeds on electricity alone. Then, if more power is needed, the six-liter V8 engine’s output is smoothly blended with the output from a battery-powered motor. When the SUV is coasting or braking, the motor becomes a generator and charges the Hybrid powertrains for luxury SUVs 300-V nickel-hydride battery. One new wrinkle, active fuel management, shuts down up to half of the engine’s cylinders when their power isn’t needed, which saves gas. The electric motor also contributes more power when the engine is running on only four cylinders, letting the V8 stay in that gas-saving mode longer.

The vehicle carries an exhaust system and resonator tuned for both four and eight-cylinder operation. So passengers aren’t bothered by noise and the engine still puts out a “pleasant” exhaust note. A 300-V air-conditioning compressor limits vibrations and lets the air conditioner cool the interior when the gas engine is off. And 42-V variableassist power steering also cuts vibrations and saves up to 0.5 mpg by reducing parasitic losses common to belt-driven hydraulic power steering.

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.