"Then there was the item that by late 1986 was creating considerable conflict between GM-H and the HDT, namely the 'energy polariser'.
... The HDT press release described the 'polariser' briefly as "a new development, which improves overall vehicle efficiency, ride comfort and stability." Among the claims made by Peter Brock for his invention were that it enabled a car tuned for super petrol to run ULP with no ill effects whatsoever. Such a claim is in defiance of all normal logic, but Brock insisted on the truth of it. He admitted that this was "way out thinking" but it was clear that his faith was beyond question or challenge. On the other hand, GM-H dismissed it in these terms; "as far as the energy polariser is concerned GM-H can see no technical merit in it and cannot endorse its use". Peter Brock's clash with GM-H peaked in February '87, with the announcement that the long-standing relationship with HDT and GM-H was over. "
And then from www.skeptics.com.au
"In 1982, Australian Skeptics instituted an award to be presented annually at the National Convention to individuals or organisations who made the most outrageous claim of a paranormal or pseudoscientific nature in the preceding year. ...
The next award went to an Australian sporting icon. In 1986, Peter Brock, Australia's premier touring car driver, became involved in promoting an "energy polariser" which, he alleged, when attached to the firewall of a car, improved its performance in all fields. The device was not connected to any of the vehicle systems and supposedly worked by application of mysterious "energies unknown to science". Along with motoring journals, the Skeptics conducted an investigation of the device and found that there was no basis to the claims made. The fallout from this affair saw Brock severing his relationship with General Motors, his long time sponsors and with a number of his colleagues. The publicity associated with the case saw the device withdrawn from sale."
It sounds like the fuel didn't even run through this device at all.