More miles per litre of fuel
The figures demonstrate that the car undertook approximately 150 more miles using Oxytane than would have been possible without.
The car ran very smoothly and quietly though it is hard to say whether there was any improvement in performance.
When tank was refilled with no additional Oxytane the estimated total mileage for tank went up to 458 miles (+135 miles versus 323 miles of original full take estimate without Oxytane) and after 235 miles of driving the tank computer showed there were 223 miles left in the tank. This indicates that there were some residual benefits of using Oxytane in the previous tank.
NB: the tank computer estimates prior to using Oxytane were proven to be fairly reliable.