Essex-based Energy Dynamics is introducing FX1 in the UK next month. When added to oil it will, the company says, reduce fuel consumption by an average of 6.7 per cent, increase power by 3.9 per cent, and cut polluting emissions.
But the company says it has not received payment for an initial sample of 50 barrels, worth pounds 50,000, delivered to the US company Identicar in 1994. Identicar has since claimed ownership of the product and US distributors are reluctant to take sides.
"We indisputably own the product," a spokesman for Energy Dynamics said. "Any claims being made by John Harris [president of Identicar] are false. We can prove it, and are not worried about any claims he may make or be making." Mr Harris could not be contacted.
Many engine lubricant additives have been trumpeted as "revolutionary" in the past and have failed to live up to their promise, but FX1 appears to have had all its claims substantiated by independent government laboratory tests.
Energy Dynamics says that when added to a mineral-based oil it offers the same performance as a top-of-the-range synthetic oil for "significantly less" money.
This cheaper high-performance formula, combined with reduced fuel and maintenance costs, could save the British motorist a "significant" amount of money.
"The last five years have been spent refining the formula and sales in industry have been successful," said technical consultant Matthew Shephard of Energy Dynamics. "However, we believe that the retail market is more suited to our product."