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Austrian testing firm AVL and GM have developed new criteria and assessment categories for AVL Drive, a real-time analytical tool to measure and score vehicle driveability objectively.

Increased application of fuel saving technologies such as six-speed automatic transmissions, early gear-shifting strategies and cylinder de-activation means more transition phases.

These affect driveability and operator comfort, but quantifying their effect is difficult. Transducers calibrated to the response of the human body measure the inputs experienced by the driver, such as acceleration, shock, noise and vibration. These signals change during transition phases.

The tool also logs vehicle operating parameters such as throttle position, engine and road speed and gear selection.

GM’s latest family of heavy-duty pick-up trucks incorporates several new powertrain elements. AVL’s software would have been ideal for developing them but the vehicle category wasn’t then available.

GM project engineer Eric Schutt said: “This was GM’s first use of AVL Drive in a full production programme. As part of the development process we identified changes we wanted. AVL added the whole pick-up truck class. We wanted cylinder de-activation as a criterion that could be measured and triggered in the tool: AVL added that too.”

The software is pre-programmed with benchmarking data, accessed through a neural network. This enables driveability to be analysed, rated and compared with competitor vehicles in real time through the full range of operating conditions.

GM used the tool during development of the Chevrolet Silverado and GMC Sierra, integrating it into the engine and transmission calibration process. The firm was able to incorporate the features and reduce CO2 emissions without affecting driveability.

“The complexity of new vehicles means we’re at a point where quantifying the timing and effects of transitions benefits from an objective tool,” said Schutt.