Hybrid vehicles such as the highly popular Toyota Prius have an electric motor and a fossil-fuel engine, which are deployed at different stages of the driving cycle to deliver fuel economies.

In contrast, "intelligent" cars are conventional vehicles would be fitted with telematics.

These are sensors and receivers that work in a network, swapping information about the traffic ahead in order to speed up the car or slow it down so that the ride is smooth and avoids the stop-start phenomenon that so drains fuel.

The technology for road telematics already exists, but given questions on safety and other issues that surround it, it is only being deployed in a small handful of field tests.

Engineers at Australia's University of Melbourne compared how the two novel technologies matched up on fuel efficiency.

They used an unconverted saloon, or sedan, as the benchmark and three different driving cycles, configured to the Australian, American and European urban lifestyles, for the test runs.

A hybrid version of the car would deliver fuel economy of 15-25 percent over the unconverted vehicle, they calculated.

But this saving was matched when the benchmark car was fitted with basic telematics that predicted traffic flows as little as seven seconds ahead, as determined by the Australian drive cycle.

Under the US and European cycles, hybrid-matching fuel economy was reached with a look-ahead predictability of less than 60 seconds.

If the predictability was boosted to 180 seconds, the newly-intelligent car was 33 percent more fuel-efficient than when it was unconverted.

In their computations, the authors included factors such as the presence of "unintelligent" cars on the road that would impede the efficiency of the look-forward technology.

The study appears in Transport Research Part C: Emerging Technologies, a journal published by the Elsevier group.

The authors say the figures are useful contribution in the public-policy debate about fuel economy, which is also a key issue in the fight against greenhouse-gas emissions.

If simple and effective sensor networks can be installed in cities and cars, people who are interested in fuel-savings benefits will question the value of purchasing hybrids, given their hefty price tag, the paper suggests.

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